Quick answers
- Is CVE-2026-58100 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-58100 being exploited in the wild.
- How severe is CVE-2026-58100?
- Informational severity, published 15 October 2026.
- Which products and versions are affected?
- Freebsd 15.1 (prior to 15.1-RELEASE-p4).
- Is there a fix for CVE-2026-58100?
- Yes: fixed in FreeBSD 15.1-RELEASE-p4 and later; stable/15 after commit 5db05b5dedf3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-58100 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-58100?
- Check whether you run Freebsd at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: FreeBSD 15.1-RELEASE-p4 and later; stable/15 after commit 5db05b5dedf3
Technical details
CVE-2026-58100 is an out-of-bounds read in kqueue_fork_copy_knote() where file descriptor numbers are used to index into the child's file descriptor table without bounds checking. Because the child's FD table is copied before knotes are transferred, a concurrent thread in the parent can grow the parent's table and register knotes with FD numbers beyond the child's table bounds, causing an out-of-bounds read. This is a race condition requiring local access.
Affected products
- FreeBSD FreeBSD 15.1 (prior to 15.1-RELEASE-p4)
Timeline
- 2026-09-29: disclosed: FreeBSD Security Advisory FreeBSD-SA-26:65.kqueue published
- 2026-09-29: patched: Corrections committed to stable/15 and releng/15.1