Use After Free in FreeBSD

CVE-2026-5398

The implementation of TIOCNOTTY failed to clear a back-pointer from the structure representing the controlling terminal to the calling process' session. If the invoking process then exits, the terminal structure may end up containing a pointer to freed memory. A malicious process can abuse the dangling pointer to grant itself root privileges.

Vulnerability class: Use-After-Free

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.4 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (6.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 6.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-5398: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

  • FreeBSD — versions 14.3, 13.5, 15.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-5398?
CVE-2026-5398 is a high-severity vulnerability in FreeBSD, classified under Use After Free. CVSS score: 8.4/10. Published 2026-04-22.
How severe is CVE-2026-5398?
High severity. CVSS v3 base score is 8.4 out of 10.