CVE-2026-42945 — NGINX ngx_http_rewrite_module vulnerability

Description (CNA)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when the rewrite directive is followed by a rewrite, if, or set directive and an unnamed Perl-Compatible Regular Expression (PCRE) capture (for example, $1, $2) with a replacement string that includes a question mark (?). An unauthenticated attacker along with conditions beyond its 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.

Affected (CNA)

Vendor / product	Versions
F5 / NGINX Plus	unaffected R37 before *; affected R36 before R36 P4; affected R32 before R32 P6
F5 / NGINX Open Source	unaffected 1.31.0 before *; affected 0.6.27 before 1.30.1

CWE

CWE-122

References

https://my.f5.com/manage/s/article/K000161019

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

CVE

No English description supplied.

redhat-SADP

A flaw was found in NGINX, specifically within the ngx_http_rewrite_module. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests under specific rewrite configurations. This can lead to a heap buffer overflow in the NGINX worker process, which may result in arbitrary code execution if Address Space Layout Randomization (ASLR), a security technique to prevent exploitation, is disabled. Otherwise, this flaw causes a denial of service due to a restart of the NGINX worker process.