UBUNTU-CVE-2026-42055

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected Systems

• ubuntu•nginx

  all | all | all | all | all

References (6)

• https://ubuntu.com/security/CVE-2026-42055
• https://www.cve.org/CVERecord?id=CVE-2026-42055
• https://my.f5.com/manage/s/article/K000161584
• https://github.com/nginx/nginx/commit/58a7bc3406ac8b9dc0e0afafc69ba42df56009e3
• https://github.com/nginx/nginx/commit/26d824ec3a2f819300edce0ab3b055751c9843ff
• https://github.com/nginx/nginx/commit/131be8514da8985b15b74150521afedbf9cc4ea3