A single misplaced exclamation point in the Linux kernel introduced a use-after-free bug that allows unprivileged users to gain root access. The flaw, tracked as CVE-2026-23111, resides in the nf_tables subsystem used for packet filtering. It was fixed in February and backported to major distributions.
Researchers at Exodus Intelligence detailed the vulnerability in a blog post published Monday. The bug stems from an error in handling verdict maps and catchall elements during deletion, enabling attackers to decrement reference counters arbitrarily and free memory objects still in use. The issue affects Debian and Ubuntu systems. Exodus Intelligence reported a proof-of-concept exploit achieving greater than 99 percent stability on idle systems. FuzzingLabs previously demonstrated a similar exploit in April. CVE-2026-23111 is one of several recent elevation-of-privilege flaws in Linux. When combined with other exploits, it can bypass sandbox defenses.
