# CVE-2026-101308: FreeBSD sound(4) use-after-free in buffer resize TOCTOU race

Source: https://junglewise.ai/threats/cve-2026-101308-when-an-audio-channel-s-buffer-needs-to-be-resized-the-sound-4  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-19  
License: CC BY 4.0 with a link back

CVE-2026-101308 · Severity: medium · CVSS 5.5 · Published 2026-10-15

FreeBSD's sound(4) driver manages audio device buffers that applications can memory-map for low-latency audio I/O. A race condition exists between buffer resizing and memory mapping that allows an unprivileged local user with sound device access to free a buffer that has been mapped by another thread, causing a use-after-free and potential privilege escalation.

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

## Quick answers

**Is CVE-2026-101308 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101308 being exploited in the wild.

**How severe is CVE-2026-101308?** Medium severity, with a CVSS score of 5.5, published 15 October 2026.

**Which products and versions are affected?** Freebsd all supported versions; patched in 15.1-RELEASE-p5, 14.5-RELEASE-p2, 14.4-RELEASE-p11, and stable branches.

**Is there a fix for CVE-2026-101308?** Yes: fixed in FreeBSD 15.1-RELEASE-p5, 14.5-RELEASE-p2, 14.4-RELEASE-p11 and later. Until then: No workaround is available. Systems without sound devices are unaffected. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101308 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-101308?** 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-p5, 14.5-RELEASE-p2, 14.4-RELEASE-p11 and later

No workaround is available. Systems without sound devices are unaffected.

## Technical details

The sound(4) driver checks if a buffer is memory-mapped before resizing, but drops the channel lock during new buffer allocation, creating a time-of-check-time-of-use (TOCTOU) window. During this window, another thread can successfully mmap the buffer, after which the resize path frees the now-mapped buffer without rechecking. An unprivileged local attacker with access to /dev/dsp or similar audio device nodes can trigger this use-after-free to gain kernel code execution and escalate privileges.

## Affected products

- FreeBSD FreeBSD all supported versions; patched in 15.1-RELEASE-p5, 14.5-RELEASE-p2, 14.4-RELEASE-p11, and stable branches

## Timeline

- 2026-10-14: disclosed: Security advisory announced
- 2026-10-14: patched: Patches applied to stable/15, stable/14, and release branches

## References

- [https://security.freebsd.org/advisories/FreeBSD-SA-26:71.sound.asc](https://security.freebsd.org/advisories/FreeBSD-SA-26:71.sound.asc)

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