CVE-2026-58099
FreeBSD: Memory safety bugs in kqueue copy-on-fork implementation
FreeBSD FreeBSDOperating systems
CVSS
7.0HighExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.10%Chance of exploitation activity in the next 30 days, higher than 0% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
What fixes it
No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.
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.
Text from CVE List
Affected versions 1
- FreeBSDaffected: 15.1-RELEASE before p4CVE List