NGINX ngx_http_rewrite_module vulnerability_CVE-2026-9256

8.1 / 10

HIGH

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

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.

Basic Information

ID CVE-2026-9256

Source f5

Published May 22, 2026 at 14:11

Modified May 22, 2026 at 14:27

Affected Product

Vendor F5

Product NGINX Plus

Version 37.0

Affected Versions F5 NGINX Plus 37.0
F5 NGINX Plus R36
F5 NGINX Plus R32
F5 NGINX Open Source 1.31.0
F5 NGINX Open Source 1.30.0
F5 NGINX Open Source 0.1.17

CWE Classification

CWE-122

References

my.f5.com /manage/s/article/K000161377

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