PT-2026-42776 · F5 · Nginx Open Source+1
Published
2026-05-22
·
Updated
2026-05-22
·
CVE-2026-9256
CVSS v3.1
8.1
High
| Vector | AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
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.
Fix
Heap Based Buffer Overflow
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Weakness Enumeration
Related Identifiers
Affected Products
Nginx Open Source
Nginx Plus