# CVE-2026-58091: FreeBSD sound driver use-after-free in SNDCTL_DSP_SYNCSTART ioctl

Source: https://junglewise.ai/threats/cve-2026-58091-freebsd-sound-driver-use-after-free-in-sndctl-dsp-syncstart-ioctl  
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-2026-58091 · Severity: high · CVSS 7.8 · Published 2026-08-26

FreeBSD's sound driver handles synchronization of multiple audio devices through a kernel ioctl interface. A use-after-free vulnerability in this interface allows unprivileged local users on systems with multiple audio devices to escalate privileges by exploiting a race condition in lock management. Systems with zero or one sound device are unaffected.

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

## Quick answers

**Is CVE-2026-58091 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-58091 being exploited in the wild.

**How severe is CVE-2026-58091?** High severity, with a CVSS score of 7.8, published 26 August 2026.

**Which products and versions are affected?** Freebsd 15.0, 15.1, 14.4 and earlier supported versions.

**Is there a fix for CVE-2026-58091?** A patch was published on 2026-08-25: Patches released for stable/15, releng/15.1, releng/15.0, stable/14, and releng/14.4 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-58091 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-58091?** 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 SNDCTL_DSP_SYNCSTART ioctl implementation attempts to acquire locks on all channels in a sync group. When locking a channel would block, it releases the sync group list lock and sleeps. Upon reawakening, the sync group structure may have been freed, but the implementation does not validate this, resulting in a use-after-free vulnerability. The vulnerability requires local access and multiple audio devices present on the system. An unprivileged local user can exploit this race condition to achieve privilege escalation. Patches were issued on 2026-08-25 for all supported FreeBSD branches.

## Affected products

- FreeBSD FreeBSD 15.0, 15.1, 14.4 and earlier supported versions

## Timeline

- 2026-08-25: disclosed: FreeBSD Security Advisory SA-26:58 published
- 2026-08-25: patched: Patches released for stable/15, releng/15.1, releng/15.0, stable/14, and releng/14.4

## References

- [https://security.freebsd.org/advisories/FreeBSD-SA-26:58.sound.asc](https://security.freebsd.org/advisories/FreeBSD-SA-26:58.sound.asc)

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