← back
CVE-2026-9256criticalCWE-122

NGINX ngx_http_rewrite_module vulnerability

53Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 9.2epss 10%
from disclosure to weapon2 days
Published on NVDMay 22
1st PoC+2d
exploitation probability
10%top 5% of all CVEs
observed exploitation
nono source reports it
4 public exploit(s)
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.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.