Haproxy
CVE-2023-40225
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V4 - API and Web Service HTTP request consistency
|
| Impact | CVSS score of 7.2 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could manipulate HTTP request interpretation between frontend and backend servers by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAI
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.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Enforce strict HTTP parsing, normalize requests at proxy layer, use HTTP/2 end-to-end, reject ambiguous headers.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444), which allows attackers to manipulate HTTP request interpretation between frontend and backend servers. 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 headers, violating RFC 9110 section 8.6. In uncommon cases, an HTTP/1 server behind HAProxy may interpret the payload as an extra request. Affected products include: Haproxy. Version information: through 2.0.32.
Know when Haproxy gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
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 headers, violating RFC 9110 section 8.6. In uncommon cases, an HTTP/1 server behind HAProxy may interpret the payload as an extra request.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
HTTP request smuggling exploits inconsistencies in how front-end and back-end servers parse HTTP message boundaries.
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
Affected Products (CPE)NVD
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
An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform an HTTP request
A flaw was found in HAProxy before 2.0.6. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no
headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the mastercactapus caddy-proxyprotocol plugin throu
HAProxy through 2.0.2 allows attackers to cause a denial of service (ha_panic) via vectors related to htx_manage_client_
The HAProxy package before 0.59_16 for pfSense has XSS via the desc (aka Description) or table_actionsaclN parameter, re
Unauthenticated remote attackers can gain full administrative control of the HAProxy Data Plane API - and through it the
The HTTP/2 implementation in HAProxy before 2.0.10 mishandles headers, as demonstrated by carriage return (CR, ASCII 0xd
HAProxy before 2.7.3 may allow a bypass of access control because HTTP/1 headers are inadvertently lost in some situatio
FastCGI framing desynchronization in HAProxy through 3.4.0 stems from a 16-bit integer overflow in the fcgi_conn demux r
Multiple integer overflows in the http_request_forward_body function in proto_http.c in HAProxy 1.5-dev23 before 1.5.4 a
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 w
Exploit-DB