CVE-2026-58100: kqueue_fork_copy_knote() indexed into the child's file descriptor table using a knote's file descriptor number

Routine

HIGH 7.0MITIGATE

CVE-2026-58100 is a high-severity flaw (CVSS 7.0) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.0 (High)
Attack vector	Local
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 99%)
CISA exploited list	No
Weakness	CWE-125, CWE-362
Published	2026-10-15
Last modified	2026-10-19

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-15 07:18 UTCPublished CVE record published
2026-10-19 21:01 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 15.1 · 15.1 p1 · 15.1 p2 · 15.1 p3

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.1

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-58100?

freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-58100 being exploited?

CVE-2026-58100 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-58100 affect?

CVE-2026-58100 affects freebsd. Severity is high (CVSS 7.0). 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 cou

How urgent is CVE-2026-58100?

Priority 25/100. High severity

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References

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