Critical Check Point Vulnerability Allows Root Code Execution via Long Username

• •CVE-2026-91843 allows root code execution via a long username.
• •Check Point released a patch on September 16, 2026, urging immediate application.
• •This vulnerability is the fifth critical issue in Check Point's management servers since July.

A critical vulnerability in Check Point's Security Management and Log Servers, tracked as CVE-2026-91843, allows unauthenticated attackers to run code as root by sending a network request with an excessively long username. Rated 9.8 on the CVSS scale, this stack overflow occurs in the login process before authentication. Check Point released a patch on September 16, 2026, through its LivePatch channel, advising immediate application for customers without automatic updates. The vulnerability affects multiple branches, including R82.10 and R82.20, with the latter lacking a protective Jumbo Hotfix. No evidence of exploitation has been reported, but the potential impact is severe. The flaw marks the fifth critical unauthenticated management server issue since July 2026, highlighting escalating security challenges for Check Point. Censys identified approximately 3,836 hosts worldwide that may be vulnerable, although actual exposure depends on version checks and patch deployment.