What’s Vulnerable › Vulnerabilities

CVE-2026-9256: NGINX ngx_http_rewrite_module vulnerability

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap 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 products

How to fix

Upgrade to a fixed version: F5 NGINX Gateway Fabric 2.6.2; F5 NGINX Ingress Controller 5.4.3; F5 NGINX Instance Manager 2.22.1; F5 NGINX Open Source 1.30.2; F5 NGINX Plus r36; RedHat Update Infrastructure 5.2. Check the vendor advisory for mitigations.

References

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