NGINX
CVE-2026-9256: NGINX ngx_http_rewrite_module vulnerability
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| NGINX Plus 37.0 | 37.0.1.1 or later |
| NGINX Plus R36 | R36 P5 or later |
| NGINX Plus R32 | R32 P7 or later |
| NGINX Open Source 1.31 | 1.31.1 or later |
| NGINX Open Source 1.30 | 1.30.2 or later |
| NGINX Open Source 0.1.17 to 0.9.7 | Upgrade past 0.9.7; see the advisory |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 12 Oct 2026.