Bypassing NAXSI Web Application Firewall (WAF) via `X-Forwarded-For` IP Matching in Versions 1.3 to 1.6

CVE-2023-45132 · CRITICAL Severity

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NAXSI is an open-source maintenance web application firewall (WAF) for NGINX. An issue present starting in version 1.3 and prior to version 1.6 allows someone to bypass the WAF when a malicious `X-Forwarded-For` IP matches `IgnoreIP` `IgnoreCIDR` rules. This old code was arranged to allow older NGINX versions to also support `IgnoreIP` `IgnoreCIDR` when multiple reverse proxies were present. The issue is patched in version 1.6. As a workaround, do not set any `IgnoreIP` `IgnoreCIDR` for older versions.

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