CVE-2026-42934: NGINX ngx_http_charset_module vulnerability

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-13 · updated 2026-10-26
Weakness: CWE-125

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset, source_charset, and charset_map and proxy_pass with disabled buffering ("off") directives are configured, unauthenticated attackers can send requests that with conditions beyond the attackers' 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.

Affected products

F5 Dos: from 4.3.0 through 4.7.0; 4.8.0
F5 NGINX Gateway Fabric: from 1.3.0 through 1.6.2; from 2.0.0 through 2.6.0
F5 NGINX Ingress Controller: from 3.5.0 through 3.7.2; from 4.0.0 through 4.0.1; from 5.0.0 through 5.4.2
F5 NGINX Instance Manager: from 2.16.0 through 2.22.0
F5 NGINX Open Source: from 0.3.50 through 0.9.7; from 1.0.0 through 1.30.0
F5 NGINX Plus: from r32 through r36
F5 Waf: from 4.9.0 through 4.16.0; from 5.1.0 through 5.8.0; from 5.9.0 through 5.12.1

References

https://my.f5.com/manage/s/article/K000161028

Get alerted when CVE-2026-42934 or the next vulnerability affects your stack