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CVE-2026-42533

f5 · nginx gateway fabric

Published
CVSS8.1
Severityhigh
WeaknessCWE-122
ExploitedNot in CISA KEV

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Description

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. 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 ca

References

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Our coverage of CVE-2026-42533

CVE-2026-42533critical

Critical NGINX Vulnerability Can Crash Workers and May Allow Remote Code Execution

A critical vulnerability, tracked as CVE-2026-42533, has been reported in NGINX, a widely used web server and reverse proxy. This flaw is said to potentially enable remote attackers to crash worker processes and may, in certain configurations, lead to remote code execution. The vulnerability affects a broad range of NGINX versions, specifically from 0.9.6 up to 1.31.2.