Experts warn of active exploitation of critical NGINX flaw CVE-2026-42945

A critical vulnerability in NGINX, identified as CVE-2026-42945, is being actively exploited, enabling attackers to crash systems or potentially execute code through malicious HTTP requests. This high-severity flaw, with a CVSS v4 score of 9.2, affects both NGINX Plus and NGINX Open Source, and its exploitation has been observed by VulnCheck just days after its disclosure¹. The vulnerability is a heap buffer overflow, allowing attackers to send specially crafted HTTP requests to vulnerable systems. Given its recent disclosure and active exploitation, entities using NGINX Plus or NGINX Open Source should prioritize patching and monitoring their systems for signs of exploitation. The active exploitation of CVE-2026-42945 expands the attack surface, making it essential for practitioners to assess their exposure and take prompt action to mitigate potential risks. This vulnerability's exploitation highlights the need for swift patch management and vigilance in protecting against emerging threats.