NGINX CVE-2026-42533: Critical Heap Buffer Overflow Vulnerability
In July 2026, a critical vulnerability identified as CVE-2026-42533 was discovered in NGINX Plus and NGINX Open Source. This heap buffer overflow flaw arises when the `map` directive utilizes regex matching, and a string expression references the map's regex capture variables before the map output variable. An unauthenticated attacker can exploit this by sending specially crafted HTTP requests, leading to a denial-of-service (DoS) condition through worker process crashes. In environments where Address Space Layout Randomization (ASLR) is disabled or bypassed, remote code execution (RCE) becomes possible. ([ionix.io](https://www.ionix.io/threat-center/cve-2026-42533/?utm_source=openai)) The widespread use of NGINX in web servers and reverse proxies amplifies the potential impact of this vulnerability. Organizations relying on NGINX are urged to update to the patched versions—NGINX 1.30.4 (stable), 1.31.3 (mainline), or NGINX Plus 37.0.3.1—to mitigate the risk of exploitation. ([ionix.io](https://www.ionix.io/threat-center/cve-2026-42533/?utm_source=openai))
Kill Chain