Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| FreeBSD | FreeBSD | 15.1-RELEASE – < p3, 15.0-RELEASE – < p13, 14.4-RELEASE – < p9 | p3 |
Advisories 1
- WID-SEC-2026-3034 FreeBSD Project FreeBSD OS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 25, 2026
References
- https://security.freebsd.org/advisories/FreeBSD-SA-26:62.tty.asc vendor-advisory