CVE-2026-42934 NGINX ngx_http_charset_module vulnerability
Unauthenticated attackers can trigger a heap buffer over-read in NGINX, causing memory disclosure or service restarts when specific charset and proxy configurations are enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42934?
CVE-2026-42934 is a medium-severity vulnerability in F5 NGINX Open Source, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-42934?
2 open source packages ship an affected version, including nginx and nginx-gateway. It affects 7 products.
| Package | Affected | Fixed in |
|---|---|---|
nginx Bitnami | From 0.3.50 | 1.30.1 |
nginx-gateway Bitnami | From 0.3.50 | 1.30.1 |
Products include F5 Dos, F5 Nginx Gateway Fabric, F5 Nginx Ingress Controller, F5 Nginx Instance Manager, F5 Nginx Open Source, F5 Nginx Plus and 1 more.
How do I fix CVE-2026-42934?
Upgrade nginx to 1.30.1 or later.
Is CVE-2026-42934 being exploited?
There is no known exploitation of CVE-2026-42934 in the wild and no public exploit code.
Other vulnerabilities in F5 NGINX Open Source
- CVE-2026-42055 NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability
- CVE-2026-42945 NGINX ngx_http_rewrite_module vulnerability
- CVE-2026-42946 NGINX ngx_http_scgi_module and ngx_http_uwsgi_module vulnerability
- CVE-2026-40460 NGINX ngx_quic_module vulnerability
- CVE-2026-48142 NGINX ngx_http_charset_module vulnerability
Sources
Also known as ALPINE-CVE-2026-42934, AZL-86853, BELL-CVE-2026-42934, BIT-nginx-2026-42934, BIT-nginx-gateway-2026-42934, DEBIAN-CVE-2026-42934 and 8 more.