Vulnerability · Published Oct 15, 2026 · Assigned by freebsd
CVE-2026-58099Memory safety bugs in kqueue copy-on-fork implementation
High 7.0
In plain English
A high-severity race condition in FreeBSD from FreeBSD. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).
Official description
When copying knotes from a parent kqueue to a child, the copy code did not correctly exclude marker knotes (used internally to track list traversal position) before marking them as in-flux and releasing the kqueue lock. If another thread freed a marker while the lock was dropped, the subsequent in-flux decrement operated on freed memory. An unprivileged local user may be able to exploit these races to escalate privileges.
Affected products (as reported)
Weakness: CWE-362, CWE-416 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H