Exploit Released for Unpatched Ubuntu Linux Flaw Enabling Host-Root Container Escape

A use-after-free vulnerability in the Linux kernel's AF_UNIX socket subsystem, tracked as CVE-2026-80521, enables container escape to gain root privileges on the host. The flaw affects unpatched Ubuntu 26.04, 24.04, and 22.04 LTS releases, despite an upstream fix being available since August 6, 2026. Security firm DepthFirst released exploit code targeting Ubuntu 26.04, demonstrating the practical risk of containerized environments where default seccomp policies allow access to AF_UNIX sockets. Although no active attacks have been confirmed, the vulnerability undermines container security assumptions, especially as AI-assisted research accelerates discovery of such flaws.

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