🔴 Discussion: CVE-2026-42945 – Heap Buffer Overflow in NGINX (ngx_http_rewrite_module) #5694
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Hello everyone,
A critical vulnerability has been identified in NGINX related to the ngx_http_rewrite_module, specifically involving a heap buffer overflow when processing rewrite directives (rewrite, if, set) combined with non-named PCRE captures.
📌 Impact
⚠️ Exploitation conditions
Potential DoS (worker process crashes via crafted HTTP requests)
In specific scenarios, possible RCE (Remote Code Execution)
CVSS: 9.2 (Critical)
The issue can be triggered when:
HTTP requests are specially crafted and manipulated
Usage of rewrite/if/set directives with specific regex patterns
Interaction with non-named PCRE captures
🧠 Affected versions
Still under detailed assessment, but it is recommended to assume risk for versions prior to the latest patched releases.
✅ Recommended mitigation
Upgrade immediately to:
NGINX 1.30.2+
or NGINX 1.31.1+
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