CVE-2026-23014: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23014 is a use-after-free vulnerability in the Linux kernel's perf subsystem, specifically in the perf_swevent hrtimer implementation. Due to a change in hrtimer_try_to_cancel() within perf_swevent_cancel_hrtimer(), the hrtimer can remain active when a perf event is freed, creating a use-after-free condition. Affected kernel versions include 6.17.8 up to (but not including) 6.18, 6.18.0 through 6.18.5, and 6.19-rc1 through 6.19-rc8. It was published on January 28, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat CVE, Red Hat Bugzilla).

The root cause is a use-after-free (CWE-416) in the Linux kernel's software perf event (swevent) hrtimer handling. When perf_swevent_cancel_hrtimer() calls hrtimer_try_to_cancel(), the hrtimer may not be fully stopped before the associated perf_event structure is freed; subsequent hrtimer callbacks then access freed memory. The fix installs a perf_event::destroy handler that calls the blocking hrtimer_cancel() on the event free path, ensuring the timer is fully stopped before memory is released. Patches are available as kernel commits deee9dfb111ab00f9dfd46c0c7e36656b80f5235 and ff5860f5088e9076ebcccf05a6ca709d5935cfa9 (Red Hat Bugzilla, Kernel Patch 1, Kernel Patch 2).

A local attacker with low-level privileges can exploit this use-after-free condition to trigger memory corruption, potentially leading to a denial of service (system crash or instability) or privilege escalation. The vulnerability has no impact on confidentiality or integrity per the CVSS scoring, but the availability impact is rated High. It is particularly relevant in multi-user systems and containerized environments where untrusted local users may have access to perf event interfaces (Red Hat CVE).

Update to Linux kernel version 6.18.6 or later, or 6.19-rc5 or later, which include the upstream fixes. The specific commits resolving this issue are deee9dfb111ab00f9dfd46c0c7e36656b80f5235 and ff5860f5088e9076ebcccf05a6ca709d5935cfa9. For systems that cannot be immediately patched, restrict local access and minimize privileges for untrusted users, and monitor system logs for unexpected crashes or memory corruption errors (Red Hat CVE, Red Hat Bugzilla).