Quick answers
- Is CVE-2026-58099 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-58099 being exploited in the wild.
- How severe is CVE-2026-58099?
- Informational severity, published 15 October 2026.
- Which products and versions are affected?
- Freebsd 15.1.
- Is there a fix for CVE-2026-58099?
- Yes: fixed in FreeBSD 15.1-RELEASE-p4, 15.1-STABLE (as of 2026-09-29). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-58099 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-58099?
- 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, 15.1-STABLE (as of 2026-09-29)
Technical details
CVE-2026-58099 involves a use-after-free race: when copying knotes to a child process, marker knotes were not excluded before marking them in-flux and releasing the lock, allowing a thread to free the marker while the lock was dropped, causing subsequent operations to dereference freed memory. CVE-2026-58100 involves an out-of-bounds read in kqueue_fork_copy_knote() where a knote's file descriptor number was used without bounds checking against the child's file descriptor table. Both vulnerabilities are triggered by local threads and lead to privilege escalation.
Affected products
- FreeBSD FreeBSD 15.1
Timeline
- 2026-09-29: disclosed
- 2026-09-29: patched
- 2026-10-15: advisory