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CVE-2026-9256

HIGH CVSS: 8.1 Published: 2026-05-22 Modified: 2026-08-11

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 Platforms

Redhat Hardened ImagesF5 WafF5 DosRedhat Enterprise LinuxF5 Nginx Ingress ControllerF5 Nginx Gateway FabricF5 Nginx Open SourceRedhat DiscoveryDebian Debian LinuxF5 Nginx Plus

Weakness Type

CWE-122, CWE-122

References