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ZDI-26-784: FreeBSD Kernel kqueue Use-After-Free Local Privilege Escalation Vulnerability

FreeBSD · CVE-2026-58093 ZDI-26-784
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What is it?

The TIOCSCTTY ioctl handler drops the tty lock in order to acquire the process tree lock. After reacquiring the tty lock, the handler did not revalidate the state of the terminal, and could proceed to link a terminal that was concurrently being destroyed to the calling process' session. An unprivileged local user can exploit this race condition to escalate privileges.

Evidence

Research (1)

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
7.0
EPSS
0.1%
First seen
6 d ago
Status
confirmed

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