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18Track

TOCTOU race between sound(4) buffer resizing and mmap

FreeBSD · CVE-2026-101308
0 news outlets1 CERTs and agencies0 researchers

Assessment: Track

SSVC decision points: exploitation none, automatable no, technical impact partial, deployment low.

What is it?

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.

Evidence

Official warnings (1)
National CERTs, government cyber security agencies and the vendor’s own advisories

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
5.5
EPSS
0.1%
First seen
17 h ago
Status
confirmed

All FreeBSD vulnerabilities