# CVE-2026-58093: FreeBSD kernel use-after-free via tty ioctl race condition

Source: https://junglewise.ai/threats/cve-2026-58093-freebsd-kernel-use-after-free-via-tty-ioctl-race-condition  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-26. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-58093 · Severity: high · CVSS 7 · Published 2026-08-26

FreeBSD's terminal device management subsystem contains a race condition in the TIOCSCTTY ioctl handler that allows an unprivileged local user to exploit improper lock handling and escalate privileges. An attacker can link a terminal being destroyed to their session, gaining unauthorized elevated access to the system.

Technologies: [Freebsd](https://junglewise.ai/threats/technologies/freebsd). Vendors: [Freebsd](https://junglewise.ai/threats/vendors/freebsd).

## Quick answers

**Is CVE-2026-58093 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-58093 being exploited in the wild.

**How severe is CVE-2026-58093?** High severity, with a CVSS score of 7, published 26 August 2026.

**Which products and versions are affected?** Freebsd 14.4 before 14.4-RELEASE-p9, 15.0 before 15.0-RELEASE-p13, 15.1 before 15.1-RELEASE-p3.

**Is there a fix for CVE-2026-58093?** A patch was published on 2026-08-25: Patches released for stable/14, stable/15, releng/14.4, releng/15.0, and releng/15.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-58093 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-58093?** 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.

## Technical details

The vulnerability is a use-after-free race condition in the tty subsystem's TIOCSCTTY ioctl handler. The handler drops the tty lock to acquire the process tree lock, but upon reacquiring the tty lock, it fails to revalidate the terminal state. This allows an attacker to link a terminal that is concurrently being destroyed to their session. The vulnerability requires local access and no special privileges to trigger; an unprivileged user can exploit the timing window between lock release and reacquisition. Patches were released on 2026-08-25 for all supported FreeBSD versions (14.4, 15.0, and 15.1 release branches).

## Affected products

- FreeBSD FreeBSD 14.4 before 14.4-RELEASE-p9, 15.0 before 15.0-RELEASE-p13, 15.1 before 15.1-RELEASE-p3

## Timeline

- 2026-08-25: disclosed: FreeBSD Security Advisory SA-26:62 published
- 2026-08-25: patched: Patches released for stable/14, stable/15, releng/14.4, releng/15.0, and releng/15.1

## References

- [https://security.freebsd.org/advisories/FreeBSD-SA-26:62.tty.asc](https://security.freebsd.org/advisories/FreeBSD-SA-26:62.tty.asc)

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