Skip to main content

NGINX Plus CVE-2026-48142

MEDIUM
Out-of-bounds Read (CWE-125)
2026-06-17 f5
6.3
CVSS 4.0 · Vendor: f5
Share

Severity by source

Vendor (f5) PRIMARY
6.3 MEDIUM
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
4.8 MEDIUM

AV:N for network-delivered HTTP requests; AC:H for dual stacked prerequisites (non-default config plus content-dependent conditions); C:L and A:L for partial heap leak and worker restart only.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
SUSE
4.8 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Red Hat
4.8 MEDIUM
qualitative

Primary rating from Vendor (f5).

CVSS VectorVendor: f5

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

2
CVSS changed
Jun 22, 2026 - 16:52 NVD
4.8 (MEDIUM) 6.3 (MEDIUM)
Analysis Generated
Jun 17, 2026 - 15:38 vuln.today

DescriptionCVE.org

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their control) to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

AnalysisAI

Heap buffer over-read in NGINX Plus and NGINX Open Source's ngx_http_charset_module exposes limited worker process memory or triggers a worker restart when remote unauthenticated attackers send crafted requests against a non-default charset conversion configuration. Exploitation requires both a specific dual-directive configuration (source_charset utf-8 alongside a differing charset directive such as koi8-r in the same location block) and content-dependent conditions outside the attacker's direct control, reflected in the CVSS AC:H rating. No public exploit code exists and this CVE does not appear in the CISA KEV catalog; the vendor F5 has published advisory K000161585 with patched version guidance.

Technical ContextAI

The ngx_http_charset_module is a built-in NGINX module that performs on-the-fly character encoding conversion between declared source and target charsets for proxied or served response bodies. When a location block simultaneously declares source_charset utf-8 and a charset directive targeting a different encoding (e.g., koi8-r), the module walks multibyte UTF-8 sequences during conversion. CWE-125 (Out-of-bounds Read) identifies the root cause: the conversion logic reads beyond the boundary of its heap-allocated buffer, likely due to insufficient length validation when iterating over variable-width UTF-8 code points. CPE data confirms both F5's commercial offering (cpe:2.3:a:f5:nginx_plus) and the community distribution (cpe:2.3:a:f5:nginx_open_source) are affected, with wildcard version ranges indicating all supported releases are in scope. The vulnerability is isolated to the worker process, limiting blast radius to memory leakage or a graceful worker restart rather than full process compromise.

RemediationAI

Consult F5 advisory K000161585 at https://my.f5.com/manage/s/article/K000161585 for exact patched NGINX Plus and NGINX Open Source version numbers, which were not independently confirmed from the available intelligence. As an immediate compensating control, audit all NGINX location blocks and remove any co-occurrence of source_charset and a differing charset directive in the same block; eliminating this dual-directive combination entirely removes the vulnerable code path, though at the cost of disabling charset conversion for affected endpoints - a trade-off only acceptable if charset transcoding is non-functional for those routes. If charset conversion is a required feature and patching is delayed, restrict access to affected location blocks using NGINX's allow/deny directives or upstream network ACLs to reduce the attacker pool, accepting reduced availability in exchange for risk reduction. Do not rely on rate limiting alone as a mitigation, since a single well-timed request with suitable response content is sufficient to trigger the over-read.

CVE-2026-42945 CRITICAL POC
9.2 May 13

Heap buffer overflow in NGINX Plus and NGINX Open Source ngx_http_rewrite_module allows remote attackers to crash worker

CVE-2026-42530 CRITICAL POC
9.2 Jun 17

Use-after-free in NGINX Open Source's ngx_http_v3_module allows remote unauthenticated attackers to crash worker process

CVE-2026-42055 CRITICAL POC
9.2 Jun 17

Heap-based buffer overflow in NGINX Plus and NGINX Open Source affects deployments that proxy HTTP/2 or gRPC traffic ups

CVE-2026-9256 CRITICAL POC
9.2 May 22

Heap buffer overflow in NGINX Plus and NGINX Open Source ngx_http_rewrite_module can be triggered by unauthenticated rem

CVE-2026-42533 CRITICAL POC
9.2 Jul 15

Heap buffer overflow in NGINX Plus and NGINX Open Source lets unauthenticated remote attackers crash worker processes (D

CVE-2026-60005 HIGH
8.8 Jul 15

Limited memory disclosure and worker-process restart in NGINX Plus and NGINX Open Source arise when the optional ngx_htt

CVE-2026-27654 HIGH POC
8.8 Mar 24

Buffer overflow in NGINX's DAV module allows remote attackers to crash worker processes or manipulate file names outside

CVE-2026-27651 HIGH
8.7 Mar 24

NGINX worker process crashes via null pointer dereference in the mail authentication module when CRAM-MD5 or APOP authen

CVE-2026-27784 HIGH
8.5 Mar 24

Integer overflow in NGINX 32-bit builds with the ngx_http_mp4_module allows local attackers to corrupt or overwrite work

CVE-2026-32647 HIGH
8.5 Mar 24

NGINX Open Source and NGINX Plus contain a buffer over-read or over-write vulnerability in the ngx_http_mp4_module that

CVE-2026-56434 HIGH
8.3 Jul 15

Heap buffer over-read in the ngx_http_ssi_module of NGINX Open Source and NGINX Plus lets an unauthenticated man-in-the-

CVE-2026-42946 HIGH
8.3 May 13

Memory disclosure and denial-of-service in NGINX's SCGI and uWSGI proxy modules allow attackers with man-in-the-middle p

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected

Share

CVE-2026-48142 vulnerability details – vuln.today

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy