FreeBSD -- Memory safety bugs in kqueue copy-on-fork implementation

Problem 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 droppe...

CVE-2026-58083 Use-after-free in kqueue copy-on-fork

While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list. In addition,...

FreeBSD : FreeBSD -- Use-after-free in kqueue copy-on-fork (a4e4a74c-8bb7-11f1-a6ab-bc241121aa0a)

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the a4e4a74c-8bb7-11f1-a6ab-bc241121aa0a advisory. While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be...

FreeBSD-SA-26:50.kqueue

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-26:50.kqueue Security Advisory The FreeBSD Project Topic: Use-after-free in kqueue copy-on-fork Category: core Module: kqueue Announced: 2026-07-29 Credits:...

FreeBSD -- Use-after-free in kqueue copy-on-fork

Problem Description: While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the acti...