One-Character Linux Kernel Flaw Enables Local Root Access, Exploits Now Public
Security researchers have published a detailed, working exploit for a Linux kernel use-after-free that lets an unprivileged local user escalate to root and break out of a container. The flaw, CVE-2026-23111, sits in the kernel's nf_tables packet-filtering code and was patched upstream on February 5, 2026. Exodus Intelligence released its full technical walkthrough on June 8, and it is not even the first public exploit: FuzzingLabs published an independent reproduction back in April. The flaw came down to a single stray character, an inverted check in nf_tables, and the upstream fix removed it in one line. Ubuntu rates the flaw CVSS 7.8 (high). If your distribution's kernel package does not yet include the fix, update and reboot. The reachable setup is common: nf_tables plus unprivileged user namespaces, a Linux feature that lets an ordinary account act as root inside a private sandbox and reach kernel code it otherwise could not. Both ship by default on most desktop...
Jun 08, 2026