A critical one-character use-after-free vulnerability (CVE-2026-23111) in the Linux kernel's nf_tables packet-filtering code enables local privilege escalation from an unprivileged user to root, including container breakout. The flaw, patched since February 2026, has publicly available exploits and affects distributions with nf_tables and unprivileged user namespaces enabled, requiring urgent kernel updates and reboots to mitigate risk. This issue is part of a recent surge in Linux local-root exploits, emphasizing the need to restrict unprivileged user namespaces until patches are deployed.
https://thehackernews.com/2026/06/one-character-linux-kernel-flaw-enables.html