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Haproxy

40 CVEs product

Monthly

CVE-2026-109575 Oct 12, 19:32 CRITICAL Act Now

Unauthenticated remote attackers can gain full administrative control of the HAProxy Data Plane API - and through it the managed HAProxy load balancer - in Community and Enterprise Edition releases 2.2.0 through 3.4.3 when a specific mTLS topology is deployed. When a TLS Certificate Authority (tls_ca) and a numeric TLS port (tls_port) are configured, Server.ConfigureAPI() sets a process-global flag that disables HTTP Basic authentication on a request handler shared concurrently by HTTP, HTTPS, and UNIX-domain-socket listeners, while mutual-TLS client-certificate verification is only enforced on the HTTPS path; every other active listener therefore fails open. An attacker who can reach a plain HTTP or UNIX management endpoint can read cleartext HAProxy configuration data and replace the managed configuration via the raw configuration endpoint; no public exploit code has been identified at time of analysis, and the vendor has released fixed versions 3.4.4, 3.3.9, 3.2.17, 3.0.25 and 2.9.29 (plus EE backports).

Authentication Bypass Haproxy Data Plane Api Ee Data Plane Api Ce
NVD GitHub
CVSS 3.1
9.8
EPSS
0.4%
CVE-2026-90678 Sep 13, 03:37 HIGH PATCH This Week

HTTP request smuggling in HAProxy 3.3.0-3.4.4 affects deployments running an HTTP/3 (QUIC) frontend forwarding traffic to HTTP/1.1 backends over reused pooled connections with chunked transfer encoding. The H3 multiplexer in src/h3.c emits an untrusted client-declared DATA frame length verbatim as the HTTP/1.1 chunk size before payload bytes arrive; when a remote unauthenticated attacker under-delivers payload then ends the stream, HAProxy returns the desynchronized backend connection to the idle pool, enabling bypass of path-based frontend deny rules and exposure of concurrent clients' Authorization headers as attacker-visible request body. No public exploit code has been identified, though the attack is probabilistic and freely retryable.

Information Disclosure Haproxy
NVD GitHub VulDB
CVSS 3.1
7.5
EPSS
0.5%
CVE-2026-55204 Jun 18, 16:05 HIGH PATCH This Week

Denial of service in HAProxy through 3.4.0 allows remote unauthenticated attackers to crash worker processes by triggering HPACK dynamic table insertions under memory pressure. The flaw lives in hpack_dht_insert() in src/hpack-tbl.c, where the return value of hpack_dht_defrag() is not validated; when the memory pool is exhausted defrag returns NULL and the subsequent dereference crashes the worker. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV.

Denial Of Service Null Pointer Dereference Haproxy
NVD GitHub VulDB
CVSS 4.0
8.7
EPSS
0.4%
CVE-2026-55203 Jun 18, 16:05 CRITICAL PATCH Act Now

FastCGI framing desynchronization in HAProxy through 3.4.0 stems from a 16-bit integer overflow in the fcgi_conn demux record length (drl) field, which wraps to zero when a malicious backend sends a record with contentLength 65535 and paddingLength of 1 or more. A hostile FastCGI backend can leverage the misparse to desynchronize HAProxy's FCGI parser, leading to request routing errors, response smuggling, or memory safety issues. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; the upstream commit 5985276 widens drl to uint32_t.

Buffer Overflow Integer Overflow Haproxy
NVD GitHub VulDB
CVSS 4.0
9.0
EPSS
0.3%
CVE-2026-26081 Jul 20, 00:00 MEDIUM PATCH This Month

Missing length validation for the NEW_TOKEN format in HAProxy Community Edition 3.0 through 3.3 exposes network-accessible deployments to low-integrity and availability impacts via crafted requests. The flaw affects HAProxy Enterprise and ALOHA distributions as well, broadening the potential attack surface beyond the open-source edition. No public exploit code and no CISA KEV listing have been identified at time of analysis; patches are available across all affected release branches. Notably, the 'Information Disclosure' tag attached to this CVE conflicts with the CVSS C:N rating - defenders should consult the vendor advisory to clarify whether memory exposure is a realistic outcome.

Information Disclosure Red Hat Haproxy
NVD VulDB
CVSS 3.1
4.8
EPSS
0.4%
CVE-2026-26080 Jul 20, 00:00 LOW PATCH Monitor

HAProxy Community Edition 3.2.x and 3.3.x contains a varint mishandling defect that allows remote network clients to trigger an infinite loop or process crash, resulting in denial of service. The flaw affects Community Edition 3.2.x before 3.2.12 and 3.3.x before 3.3.3, and is explicitly confirmed to also affect HAProxy Enterprise and ALOHA commercial distributions. No public exploit has been identified and CISA has not listed this in KEV; however, HAProxy's role as a critical network gateway in many enterprise environments elevates the operational impact of even a Low-severity availability disruption.

Denial Of Service Haproxy
NVD VulDB
CVSS 3.1
3.7
EPSS
0.4%
CVE-2026-33555 Apr 13, 00:00 MEDIUM PATCH This Month

HAProxy versions 2.6 through 3.3.5 fail to validate that received HTTP/3 message body lengths match the announced Content-Length header when streams close via empty-payload frames, enabling request smuggling and backend desynchronization attacks. An unauthenticated remote attacker can exploit this via network-level HTTP/3 traffic to cause integrity violations (integrity impact rated low by CVSS), though practical exploitation requires high attack complexity. No public exploit code or active CISA KEV designation has been confirmed; the moderate CVSS 4.0 and high attack complexity suggest this is a specialized HTTP/3 protocol abuse requiring precise crafting.

Information Disclosure Haproxy
NVD GitHub VulDB
CVSS 3.1
5.8
EPSS
0.0%
CVE-2025-11230 Nov 19, 10:15 HIGH PATCH This Month

Inefficient algorithm complexity in mjson in HAProxy allows remote attackers to cause a denial of service via specially crafted JSON requests. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Haproxy Suse Aloha Appliance +2
NVD
CVSS 3.1
7.5
EPSS
0.4%
CVE-2025-59303 Oct 08, 16:15 MEDIUM This Month

Information disclosure in HAProxy Kubernetes Ingress Controller before 3.1.13 allows an authenticated attacker with Kubernetes RBAC create/update permissions on Ingress resources to obtain an ingress token secret when the non-default config-snippets feature flag is enabled. Exploitation requires two specific preconditions: the config-snippets feature flag must be active, and the attacker must already possess create/update permissions on Ingress objects. No public exploit code has been identified, and the EPSS score is 0.26% (16th percentile), indicating low likelihood of exploitation. The issue is fixed in version 3.1.13 for the open-source controller and in enterprise versions 3.0.16-ee1, 1.11.13-ee1, and 1.9.15-ee1.

Information Disclosure Kubernetes Red Hat Haproxy
NVD
CVSS 3.1
6.4
EPSS
0.3%
CVE-2024-45506 Sep 04, 15:15 HIGH This Week

HAProxy 2.9.x before 2.9.10, 3.0.x before 3.0.4, and 3.1.x through 3.1-dev6 allows a remote denial of service for HTTP/2 zero-copy forwarding (h2_send loop) under a certain set of conditions, as. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Haproxy
NVD
CVSS 3.1
7.5
EPSS
1.2%
CVE-2023-45539 Nov 28, 20:15 HIGH This Week

HAProxy before 2.8.2 accepts # as part of the URI component, which might allow remote attackers to obtain sensitive information or have unspecified other impact upon misinterpretation of a path_end. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Haproxy
NVD
CVSS 3.1
8.2
EPSS
1.5%
CVE-2023-40225 Aug 10, 21:15 HIGH POC PATCH This Week

HAProxy through 2.0.32, 2.1.x and 2.2.x through 2.2.30, 2.3.x and 2.4.x through 2.4.23, 2.5.x and 2.6.x before 2.6.15, 2.7.x before 2.7.10, and 2.8.x before 2.8.2 forwards empty Content-Length. Rated high severity (CVSS 7.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Information Disclosure Request Smuggling Haproxy
NVD GitHub
CVSS 3.1
7.2
EPSS
1.8%
CVE-2023-25950 Apr 11, 09:15 HIGH This Week

HTTP request/response smuggling vulnerability in HAProxy version 2.7.0, and 2.6.1 to 2.6.7 allows a remote attacker to alter a legitimate user's request. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Request Smuggling Haproxy
NVD
CVSS 3.1
7.3
EPSS
2.9%
CVE-2023-0836 Mar 29, 21:15 HIGH This Week

An information leak vulnerability was discovered in HAProxy 2.1, 2.2 before 2.2.27, 2.3, 2.4 before 2.4.21, 2.5 before 2.5.11, 2.6 before 2.6.8, 2.7 before 2.7.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Haproxy
NVD
CVSS 3.1
7.5
EPSS
1.2%
CVE-2023-0056 Mar 23, 21:15 MEDIUM This Month

An uncontrolled resource consumption vulnerability was discovered in HAProxy which could crash the service. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Haproxy Ceph Storage Fedora +7
NVD
CVSS 3.1
6.5
EPSS
1.8%
CVE-2023-25725 Feb 14, 19:15 CRITICAL Act Now

HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situations, aka "request smuggling." The HTTP header parsers in HAProxy may accept. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass Debian Request Smuggling Haproxy Debian Linux
NVD
CVSS 3.1
9.1
EPSS
5.5%
CVE-2022-0711 Mar 02, 22:15 HIGH PATCH This Week

A flaw was found in the way HAProxy processed HTTP responses containing the "Set-Cookie2" header. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Denial Of Service Debian Red Hat Haproxy Debian Linux +3
NVD GitHub
CVSS 3.1
7.5
EPSS
16.6%
CVE-2021-40346 Sep 08, 17:15 HIGH POC PATCH THREAT This Week

An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform an HTTP request smuggling attack, allowing an attacker to bypass all configured http-request. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Buffer Overflow Integer Overflow Debian Haproxy Debian Linux +2
NVD GitHub
CVSS 3.1
7.5
EPSS
57.9%
CVE-2021-39242 Aug 17, 19:15 HIGH This Week

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy Debian Linux Fedora +1
NVD
CVSS 3.1
7.5
EPSS
2.3%
CVE-2021-39241 Aug 17, 19:15 MEDIUM This Month

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy Debian Linux Fedora +1
NVD
CVSS 3.1
5.3
EPSS
1.8%
CVE-2021-39240 Aug 17, 19:15 HIGH This Week

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy Debian Linux Fedora +1
NVD
CVSS 3.1
7.5
EPSS
2.3%
CVE-2020-11100 Apr 02, 15:15 HIGH This Week

In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain location on the heap via a crafted HTTP/2. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RCE Buffer Overflow Memory Corruption Debian Red Hat +9
NVD
CVSS 3.1
8.8
EPSS
60.7%
CVE-2019-19330 Nov 27, 16:15 CRITICAL Act Now

The HTTP/2 implementation in HAProxy before 2.0.10 mishandles headers, as demonstrated by carriage return (CR, ASCII 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII 0x0), aka. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Canonical Haproxy Debian Linux +1
NVD
CVSS 3.1
9.8
EPSS
4.0%
CVE-2019-18277 Oct 23, 14:15 HIGH POC THREAT This Week

A flaw was found in HAProxy before 2.0.6. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Information Disclosure Request Smuggling Haproxy
NVD
CVSS 3.1
7.5
EPSS
10.0%
CVE-2019-14243 Jul 23, 22:15 Go HIGH POC PATCH This Week

headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the mastercactapus caddy-proxyprotocol plugin through 0.0.2 for Caddy, allows remote attackers to cause a denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Denial Of Service Haproxy Proxyprotocol
NVD GitHub
CVSS 3.1
7.5
EPSS
4.3%
CVE-2019-14241 Jul 23, 13:15 HIGH POC THREAT This Week

HAProxy through 2.0.2 allows attackers to cause a denial of service (ha_panic) via vectors related to htx_manage_client_side_cookies in proto_htx.c. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Denial Of Service Haproxy
NVD GitHub
CVSS 3.0
7.5
EPSS
70.2%
CVE-2019-11323 May 09, 14:29 MEDIUM This Month

HAProxy before 1.9.7 mishandles a reload with rotated keys, which triggers use of uninitialized, and very predictable, HMAC keys. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.

Information Disclosure Haproxy
NVD
CVSS 3.1
5.9
EPSS
1.2%
CVE-2019-8953 Feb 20, 16:29 MEDIUM POC PATCH THREAT This Month

The HAProxy package before 0.59_16 for pfSense has XSS via the desc (aka Description) or table_actionsaclN parameter, related to haproxy_listeners.php and haproxy_listeners_edit.php. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

PHP XSS Haproxy Netgate
NVD GitHub Exploit-DB
CVSS 3.0
6.1
EPSS
52.2%
CVE-2018-20103 Dec 12, 17:29 HIGH This Week

An issue was discovered in dns.c in HAProxy through 1.8.14. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Canonical Haproxy Openshift Container Platform +1
NVD
CVSS 3.0
7.5
EPSS
6.6%
CVE-2018-20102 Dec 12, 17:29 HIGH This Week

An out-of-bounds read in dns_validate_dns_response in dns.c was discovered in HAProxy through 1.8.14. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Buffer Overflow Information Disclosure Red Hat Canonical Haproxy +2
NVD
CVSS 3.0
7.5
EPSS
4.3%
CVE-2018-14645 Sep 21, 13:29 HIGH This Week

A flaw was discovered in the HPACK decoder of HAProxy, before 1.8.14, that is used for HTTP/2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Buffer Overflow Denial Of Service Information Disclosure Red Hat Canonical +5
NVD
CVSS 3.0
7.5
EPSS
3.0%
CVE-2018-11469 May 25, 14:29 MEDIUM This Month

Incorrect caching of responses to requests including an Authorization header in HAProxy 1.8.0 through 1.8.9 (if cache enabled) allows attackers to achieve information disclosure via an. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.

Information Disclosure Canonical Haproxy Ubuntu Linux
NVD
CVSS 3.0
5.9
EPSS
3.1%
CVE-2018-10184 May 09, 07:29 HIGH This Week

An issue was discovered in HAProxy before 1.8.8. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RCE Buffer Overflow Red Hat Haproxy Enterprise Linux
NVD
CVSS 3.0
7.5
EPSS
8.4%
CVE-2016-2102 Aug 22, 18:29 MEDIUM This Month

HAProxy statistics in openstack-tripleo-image-elements are non-authenticated over the network. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass Haproxy
NVD
CVSS 3.0
5.3
EPSS
0.0%
CVE-2016-5360 Jun 30, 17:59 HIGH Act Now

HAproxy 1.6.x before 1.6.6, when a deny comes from a reqdeny rule, allows remote attackers to cause a denial of service (uninitialized memory access and crash) or possibly have unspecified other. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Epss exploitation probability 46.1% and no vendor patch available.

Buffer Overflow Denial Of Service Canonical Haproxy Ubuntu Linux
NVD
CVSS 3.0
7.5
EPSS
46.1%
CVE-2015-3281 Jul 06, 15:59 MEDIUM PATCH This Month

The buffer_slow_realign function in HAProxy 1.5.x before 1.5.14 and 1.6-dev does not properly realign a buffer that is used for pending outgoing data, which allows remote attackers to obtain. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.

Buffer Overflow Debian Red Hat Canonical Haproxy +12
NVD
CVSS 2.0
5.0
EPSS
0.1%
CVE-2014-6269 Sep 30, 14:55 MEDIUM POC This Month

Multiple integer overflows in the http_request_forward_body function in proto_http.c in HAProxy 1.5-dev23 before 1.5.4 allow remote attackers to cause a denial of service (crash) via a large stream. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

Buffer Overflow Denial Of Service Haproxy
NVD
CVSS 2.0
5.0
EPSS
0.1%
CVE-2013-2175 Aug 19, 13:07 MEDIUM PATCH This Month

HAProxy 1.4 before 1.4.24 and 1.5 before 1.5-dev19, when configured to use hdr_ip or other "hdr_*" functions with a negative occurrence count, allows remote attackers to cause a denial of service. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity.

Denial Of Service Debian Red Hat Canonical Haproxy +3
NVD
CVSS 2.0
5.0
EPSS
0.1%
CVE-2013-1912 Apr 10, 15:55 MEDIUM This Month

Buffer overflow in HAProxy 1.4 through 1.4.22 and 1.5-dev through 1.5-dev17, when HTTP keep-alive is enabled, using HTTP keywords in TCP inspection rules, and running with rewrite rules that appends. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable. No vendor patch available.

RCE Buffer Overflow Denial Of Service Haproxy
NVD
CVSS 2.0
5.1
EPSS
0.1%
CVE-2012-2942 May 27, 20:55 MEDIUM This Month

Buffer overflow in the trash buffer in the header capture functionality in HAProxy before 1.4.21, when global.tune.bufsize is set to a value greater than the default and header rewriting is enabled,. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable. No vendor patch available.

RCE Buffer Overflow Denial Of Service Haproxy
NVD
CVSS 2.0
5.1
EPSS
0.2%
EPSS 0% CVSS 9.8
CRITICAL Act Now

Unauthenticated remote attackers can gain full administrative control of the HAProxy Data Plane API - and through it the managed HAProxy load balancer - in Community and Enterprise Edition releases 2.2.0 through 3.4.3 when a specific mTLS topology is deployed. When a TLS Certificate Authority (tls_ca) and a numeric TLS port (tls_port) are configured, Server.ConfigureAPI() sets a process-global flag that disables HTTP Basic authentication on a request handler shared concurrently by HTTP, HTTPS, and UNIX-domain-socket listeners, while mutual-TLS client-certificate verification is only enforced on the HTTPS path; every other active listener therefore fails open. An attacker who can reach a plain HTTP or UNIX management endpoint can read cleartext HAProxy configuration data and replace the managed configuration via the raw configuration endpoint; no public exploit code has been identified at time of analysis, and the vendor has released fixed versions 3.4.4, 3.3.9, 3.2.17, 3.0.25 and 2.9.29 (plus EE backports).

Authentication Bypass Haproxy Data Plane Api Ee +1
NVD GitHub
EPSS 1% CVSS 7.5
HIGH PATCH This Week

HTTP request smuggling in HAProxy 3.3.0-3.4.4 affects deployments running an HTTP/3 (QUIC) frontend forwarding traffic to HTTP/1.1 backends over reused pooled connections with chunked transfer encoding. The H3 multiplexer in src/h3.c emits an untrusted client-declared DATA frame length verbatim as the HTTP/1.1 chunk size before payload bytes arrive; when a remote unauthenticated attacker under-delivers payload then ends the stream, HAProxy returns the desynchronized backend connection to the idle pool, enabling bypass of path-based frontend deny rules and exposure of concurrent clients' Authorization headers as attacker-visible request body. No public exploit code has been identified, though the attack is probabilistic and freely retryable.

Information Disclosure Haproxy
NVD GitHub VulDB
EPSS 0% CVSS 8.7
HIGH PATCH This Week

Denial of service in HAProxy through 3.4.0 allows remote unauthenticated attackers to crash worker processes by triggering HPACK dynamic table insertions under memory pressure. The flaw lives in hpack_dht_insert() in src/hpack-tbl.c, where the return value of hpack_dht_defrag() is not validated; when the memory pool is exhausted defrag returns NULL and the subsequent dereference crashes the worker. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV.

Denial Of Service Null Pointer Dereference Haproxy
NVD GitHub VulDB
EPSS 0% CVSS 9.0
CRITICAL PATCH Act Now

FastCGI framing desynchronization in HAProxy through 3.4.0 stems from a 16-bit integer overflow in the fcgi_conn demux record length (drl) field, which wraps to zero when a malicious backend sends a record with contentLength 65535 and paddingLength of 1 or more. A hostile FastCGI backend can leverage the misparse to desynchronize HAProxy's FCGI parser, leading to request routing errors, response smuggling, or memory safety issues. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; the upstream commit 5985276 widens drl to uint32_t.

Buffer Overflow Integer Overflow Haproxy
NVD GitHub VulDB
EPSS 0% CVSS 4.8
MEDIUM PATCH This Month

Missing length validation for the NEW_TOKEN format in HAProxy Community Edition 3.0 through 3.3 exposes network-accessible deployments to low-integrity and availability impacts via crafted requests. The flaw affects HAProxy Enterprise and ALOHA distributions as well, broadening the potential attack surface beyond the open-source edition. No public exploit code and no CISA KEV listing have been identified at time of analysis; patches are available across all affected release branches. Notably, the 'Information Disclosure' tag attached to this CVE conflicts with the CVSS C:N rating - defenders should consult the vendor advisory to clarify whether memory exposure is a realistic outcome.

Information Disclosure Red Hat Haproxy
NVD VulDB
EPSS 0% CVSS 3.7
LOW PATCH Monitor

HAProxy Community Edition 3.2.x and 3.3.x contains a varint mishandling defect that allows remote network clients to trigger an infinite loop or process crash, resulting in denial of service. The flaw affects Community Edition 3.2.x before 3.2.12 and 3.3.x before 3.3.3, and is explicitly confirmed to also affect HAProxy Enterprise and ALOHA commercial distributions. No public exploit has been identified and CISA has not listed this in KEV; however, HAProxy's role as a critical network gateway in many enterprise environments elevates the operational impact of even a Low-severity availability disruption.

Denial Of Service Haproxy
NVD VulDB
EPSS 0% CVSS 5.8
MEDIUM PATCH This Month

HAProxy versions 2.6 through 3.3.5 fail to validate that received HTTP/3 message body lengths match the announced Content-Length header when streams close via empty-payload frames, enabling request smuggling and backend desynchronization attacks. An unauthenticated remote attacker can exploit this via network-level HTTP/3 traffic to cause integrity violations (integrity impact rated low by CVSS), though practical exploitation requires high attack complexity. No public exploit code or active CISA KEV designation has been confirmed; the moderate CVSS 4.0 and high attack complexity suggest this is a specialized HTTP/3 protocol abuse requiring precise crafting.

Information Disclosure Haproxy
NVD GitHub VulDB
EPSS 0% CVSS 7.5
HIGH PATCH This Month

Inefficient algorithm complexity in mjson in HAProxy allows remote attackers to cause a denial of service via specially crafted JSON requests. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Haproxy +4
NVD
EPSS 0% CVSS 6.4
MEDIUM This Month

Information disclosure in HAProxy Kubernetes Ingress Controller before 3.1.13 allows an authenticated attacker with Kubernetes RBAC create/update permissions on Ingress resources to obtain an ingress token secret when the non-default config-snippets feature flag is enabled. Exploitation requires two specific preconditions: the config-snippets feature flag must be active, and the attacker must already possess create/update permissions on Ingress objects. No public exploit code has been identified, and the EPSS score is 0.26% (16th percentile), indicating low likelihood of exploitation. The issue is fixed in version 3.1.13 for the open-source controller and in enterprise versions 3.0.16-ee1, 1.11.13-ee1, and 1.9.15-ee1.

Information Disclosure Kubernetes Red Hat +1
NVD
EPSS 1% CVSS 7.5
HIGH This Week

HAProxy 2.9.x before 2.9.10, 3.0.x before 3.0.4, and 3.1.x through 3.1-dev6 allows a remote denial of service for HTTP/2 zero-copy forwarding (h2_send loop) under a certain set of conditions, as. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Haproxy
NVD
EPSS 2% CVSS 8.2
HIGH This Week

HAProxy before 2.8.2 accepts # as part of the URI component, which might allow remote attackers to obtain sensitive information or have unspecified other impact upon misinterpretation of a path_end. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Haproxy
NVD
EPSS 2% CVSS 7.2
HIGH POC PATCH This Week

HAProxy through 2.0.32, 2.1.x and 2.2.x through 2.2.30, 2.3.x and 2.4.x through 2.4.23, 2.5.x and 2.6.x before 2.6.15, 2.7.x before 2.7.10, and 2.8.x before 2.8.2 forwards empty Content-Length. Rated high severity (CVSS 7.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Information Disclosure Request Smuggling Haproxy
NVD GitHub
EPSS 3% CVSS 7.3
HIGH This Week

HTTP request/response smuggling vulnerability in HAProxy version 2.7.0, and 2.6.1 to 2.6.7 allows a remote attacker to alter a legitimate user's request. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Request Smuggling Haproxy
NVD
EPSS 1% CVSS 7.5
HIGH This Week

An information leak vulnerability was discovered in HAProxy 2.1, 2.2 before 2.2.27, 2.3, 2.4 before 2.4.21, 2.5 before 2.5.11, 2.6 before 2.6.8, 2.7 before 2.7.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Haproxy
NVD
EPSS 2% CVSS 6.5
MEDIUM This Month

An uncontrolled resource consumption vulnerability was discovered in HAProxy which could crash the service. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Haproxy +9
NVD
EPSS 5% CVSS 9.1
CRITICAL Act Now

HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situations, aka "request smuggling." The HTTP header parsers in HAProxy may accept. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass Debian Request Smuggling +2
NVD
EPSS 17% CVSS 7.5
HIGH PATCH This Week

A flaw was found in the way HAProxy processed HTTP responses containing the "Set-Cookie2" header. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Denial Of Service Debian Red Hat +5
NVD GitHub
EPSS 58% CVSS 7.5
HIGH POC PATCH THREAT This Week

An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform an HTTP request smuggling attack, allowing an attacker to bypass all configured http-request. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Buffer Overflow Integer Overflow Debian +4
NVD GitHub
EPSS 2% CVSS 7.5
HIGH This Week

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy +3
NVD
EPSS 2% CVSS 5.3
MEDIUM This Month

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy +3
NVD
EPSS 2% CVSS 7.5
HIGH This Week

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Haproxy +3
NVD
EPSS 61% CVSS 8.8
HIGH This Week

In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain location on the heap via a crafted HTTP/2. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RCE Buffer Overflow Memory Corruption +11
NVD
EPSS 4% CVSS 9.8
CRITICAL Act Now

The HTTP/2 implementation in HAProxy before 2.0.10 mishandles headers, as demonstrated by carriage return (CR, ASCII 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII 0x0), aka. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Information Disclosure Debian Canonical +3
NVD
EPSS 10% CVSS 7.5
HIGH POC THREAT This Week

A flaw was found in HAProxy before 2.0.6. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Information Disclosure Request Smuggling Haproxy
NVD
EPSS 4% CVSS 7.5
HIGH POC PATCH This Week

headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the mastercactapus caddy-proxyprotocol plugin through 0.0.2 for Caddy, allows remote attackers to cause a denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Denial Of Service Haproxy Proxyprotocol
NVD GitHub
EPSS 70% CVSS 7.5
HIGH POC THREAT This Week

HAProxy through 2.0.2 allows attackers to cause a denial of service (ha_panic) via vectors related to htx_manage_client_side_cookies in proto_htx.c. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Denial Of Service Haproxy
NVD GitHub
EPSS 1% CVSS 5.9
MEDIUM This Month

HAProxy before 1.9.7 mishandles a reload with rotated keys, which triggers use of uninitialized, and very predictable, HMAC keys. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.

Information Disclosure Haproxy
NVD
EPSS 52% CVSS 6.1
MEDIUM POC PATCH THREAT This Month

The HAProxy package before 0.59_16 for pfSense has XSS via the desc (aka Description) or table_actionsaclN parameter, related to haproxy_listeners.php and haproxy_listeners_edit.php. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

PHP XSS Haproxy +1
NVD GitHub Exploit-DB
EPSS 7% CVSS 7.5
HIGH This Week

An issue was discovered in dns.c in HAProxy through 1.8.14. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Denial Of Service Red Hat Canonical +3
NVD
EPSS 4% CVSS 7.5
HIGH This Week

An out-of-bounds read in dns_validate_dns_response in dns.c was discovered in HAProxy through 1.8.14. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Buffer Overflow Information Disclosure Red Hat +4
NVD
EPSS 3% CVSS 7.5
HIGH This Week

A flaw was discovered in the HPACK decoder of HAProxy, before 1.8.14, that is used for HTTP/2. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Buffer Overflow Denial Of Service Information Disclosure +7
NVD
EPSS 3% CVSS 5.9
MEDIUM This Month

Incorrect caching of responses to requests including an Authorization header in HAProxy 1.8.0 through 1.8.9 (if cache enabled) allows attackers to achieve information disclosure via an. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.

Information Disclosure Canonical Haproxy +1
NVD
EPSS 8% CVSS 7.5
HIGH This Week

An issue was discovered in HAProxy before 1.8.8. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RCE Buffer Overflow Red Hat +2
NVD
EPSS 0% CVSS 5.3
MEDIUM This Month

HAProxy statistics in openstack-tripleo-image-elements are non-authenticated over the network. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Authentication Bypass Haproxy
NVD
EPSS 46% CVSS 7.5
HIGH Act Now

HAproxy 1.6.x before 1.6.6, when a deny comes from a reqdeny rule, allows remote attackers to cause a denial of service (uninitialized memory access and crash) or possibly have unspecified other. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Epss exploitation probability 46.1% and no vendor patch available.

Buffer Overflow Denial Of Service Canonical +2
NVD
EPSS 0% CVSS 5.0
MEDIUM PATCH This Month

The buffer_slow_realign function in HAProxy 1.5.x before 1.5.14 and 1.6-dev does not properly realign a buffer that is used for pending outgoing data, which allows remote attackers to obtain. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.

Buffer Overflow Debian Red Hat +14
NVD
EPSS 0% CVSS 5.0
MEDIUM POC This Month

Multiple integer overflows in the http_request_forward_body function in proto_http.c in HAProxy 1.5-dev23 before 1.5.4 allow remote attackers to cause a denial of service (crash) via a large stream. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

Buffer Overflow Denial Of Service Haproxy
NVD
EPSS 0% CVSS 5.0
MEDIUM PATCH This Month

HAProxy 1.4 before 1.4.24 and 1.5 before 1.5-dev19, when configured to use hdr_ip or other "hdr_*" functions with a negative occurrence count, allows remote attackers to cause a denial of service. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity.

Denial Of Service Debian Red Hat +5
NVD
EPSS 0% CVSS 5.1
MEDIUM This Month

Buffer overflow in HAProxy 1.4 through 1.4.22 and 1.5-dev through 1.5-dev17, when HTTP keep-alive is enabled, using HTTP keywords in TCP inspection rules, and running with rewrite rules that appends. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable. No vendor patch available.

RCE Buffer Overflow Denial Of Service +1
NVD
EPSS 0% CVSS 5.1
MEDIUM This Month

Buffer overflow in the trash buffer in the header capture functionality in HAProxy before 1.4.21, when global.tune.bufsize is set to a value greater than the default and header rewriting is enabled,. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable. No vendor patch available.

RCE Buffer Overflow Denial Of Service +1
NVD

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