CVE-2026-9256

8.1 HIGH
Published: May 22, 2026 Modified: June 16, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://my.f5.com/manage/s/article/K000161377
Source: f5sirt@f5.com
Mitigation Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/05/22/14
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory

2 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.1 / 10.0
EPSS (Exploit Probability)
1.1%
61th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

f5