CVE-2026-42945: NGINX ngx_http_rewrite_module vulnerability

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 68.0% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-13 · updated 2026-10-26
Weakness: CWE-122

Description

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 products

F5 Dos: from 4.3.0 through 4.7.0; 4.8.0
F5 NGINX Gateway Fabric: from 1.3.0 through 1.6.2; from 2.0.0 through 2.5.1
F5 NGINX Ingress Controller: from 3.5.0 through 3.7.2; from 4.0.0 through 4.0.1; from 5.0.0 through 5.4.1
F5 NGINX Instance Manager: from 2.16.0 through 2.21.1
F5 NGINX Open Source: from 0.6.27 through 1.30.0
F5 NGINX Plus: from r32 through r36
F5 Waf: from 4.9.0 through 4.16.0; from 5.1.0 through 5.8.0; from 5.9.0 through 5.12.1

References

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