Use-After-Free Vulnerability in FreeBSD Kernel Impacting Local User Privileges

CVE-2026-58083

What is CVE-2026-58083?

A vulnerability in the FreeBSD kernel allows an unprivileged local user to exploit a race condition during the copy of knotes in the forking process. Specifically, if a knote with a timer-based filter is triggered, it can be improperly enqueued onto the kqueue's active list before the copy is finalized. This flaw can lead to a use-after-free condition, enabling the possibility of privilege escalation by manipulating the state of knotes without appropriate lock management.

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