CVE-2026-15176: F5 Nginx Open Source

High severity, CVSS 8.1. EPSS: 0.5% chance of exploitation in the next 30 days.

A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $request_filename variable. Alternatively, the same result could be achieved when the $request_filename variable is used in an access log format directive. 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. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected products

• F5 Nginx Open Source: from 1.31.0, before 1.31.7 (fixed in 1.31.7); from 0.1.29, before 1.30.6 (fixed in 1.30.6)
• F5 Nginx Plus: from 37.1.0, before 37.1.0.1 (fixed in 37.1.0.1); from 37.0.0, before 37.0.5.1 (fixed in 37.0.5.1); from R36; from R35; from R34; from R33

Published 2026-10-14. Last modified 2026-10-15.