Out-of-Bounds Read Vulnerability in FreeBSD's Kqueue System

CVE-2026-58100

What is CVE-2026-58100?

A vulnerability exists in the kqueue subsystem of FreeBSD that allows an unprivileged local user to exploit conditions leading to an out-of-bounds read. Specifically, the function kqueue_fork_copy_knote() improperly indexes the child's file descriptor table without performing necessary bounds checks. This issue arises when a parent thread modifies the parent's file descriptor table concurrently, which can lead to the registration of knotes with file descriptor numbers that exceed the limits of the child's table. If successfully exploited, this vulnerability could allow local users to gain escalated privileges.

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