CVE-2026-58100: Memory safety bugs in kqueue copy-on-fork implementation

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-15 · updated 2026-10-19
Weakness: CWE-125

Description

kqueue_fork_copy_knote() indexed into the child's file descriptor table using a knote's file descriptor number without a bounds check. Because the child's table is copied before knotes are transferred, a concurrent thread in the parent could grow the parent's table and register knotes with file descriptor numbers beyond the end of the child's table, causing an out-of-bounds read. An unprivileged local user may be able to exploit these races to escalate privileges.

Affected products

FreeBSD: 15.1, 15.1-p1, 15.1-p2, 15.1-p3

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:65.kqueue.asc

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