TI-2026-74610 Aliases CVE-2026-58099 GHSA-f53j-rp59-76p7

Race condition and use after free in FreeBSD kqueue fork copy

LOW 32CWE-362Published 2026-10-15 · Updated 2026-10-19

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-416 and the CVSS impact.

Summary

FreeBSD from 15.1-RELEASE before p4 has memory safety bugs in the kqueue copy-on-fork code. When knotes are copied from a parent kqueue to a child, marker knotes are not excluded, so another thread can free a marker while the lock is dropped and the in-flux decrement then touches freed memory (CWE-416). An unprivileged local user may be able to exploit these races to escalate privileges.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.001 0th percentileScored 2026-11-07

Fix Fixed FreeBSD (FreeBSD): p4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
FreeBSD	FreeBSD	15.1-RELEASE to before p4	p4	Patch available	CNA

FreeBSD VendorFreeBSD Affected 15.1-RELEASE to before p4 Fixed in p4 Patch available CNA

CPE configurations NVD · 4

CPE	Versions	Role	Vendor
cpe:2.3:o:freebsd:freebsd:15.1:-::::::	15.1	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p1::::::	15.1 p1	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p2::::::	15.1 p2	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p3::::::	15.1 p3	Vulnerable	FreeBSD

cpe:2.3:o:freebsd:freebsd:15.1:-:*:*:*:*:*:* Versions 15.1 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p1:*:*:*:*:*:* Versions 15.1 p1 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p2:*:*:*:*:*:* Versions 15.1 p2 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p3:*:*:*:*:*:* Versions 15.1 p3 Vulnerable ·FreeBSD

Remediation

Update FreeBSD 15.1-RELEASE to patch level p4. The fix is listed in p4.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA FreeBSD (FreeBSD) Fixed in p4

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Advisory · 2026-10-15
FreeBSD — security.freebsd.org/advisories/FreeBSD-SA-26:65.kqueue.asc
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-74611 Out-of-bounds read in FreeBSD kqueue copy-on-fork implementationPriority LOW 32
Show all 2 records → Advisory →

Timeline

2026-10-15 Threatist record created from CVE-2026-58099
2026-10-16 Alias added: GHSA-f53j-rp59-76p7
2026-10-16 CISA SSVC decision points changed
2026-10-19 CVSS score added · CISA ADP

References

Advisory 1

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

TI-2011-04182 Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT… CVSS 2.0HIGH 10.0
TI-2007-03684 Integer overflow in print-bgp.c in the BGP dissector in tcpdump 3.9.6 and earlier allows… CVSS 3.1CRITICAL 9.8
TI-2002-00376 Integer overflow in xdr_array function in RPC servers for operating systems that use… CVSS 3.1CRITICAL 9.8
TI-2024-05929 Openssh: regresshion - race condition in ssh allows rce/dos CVSS 3.1HIGH 8.1
TI-2003-00437 Off-by-one error in the fb_realpath() function, as derived from the realpath function in… CVSS 3.1CRITICAL 9.8
TI-2003-00642 The prescan function in Sendmail 8.12.9 allows remote attackers to execute arbitrary code… CVSS 2.0HIGH 10.0

See all 576 →

Sources

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