Critical Unauthenticated Admin Takeover Vulnerability in Portainer
A high-severity vulnerability (CVE-2026-55761, CVSS 7.1) exists in Portainer, an open-source container management platform. The vulnerability allows an unauthenticated attacker to gain full administrative access to an uninitialized Portainer instance within a five-minute window after startup. Successful exploitation requires network access to the instance during this window. The vulnerability impacts Portainer versions prior to 2.39.4 (LTS) and 2.43.0 (STS).