CVE-2026-5398 | Kernel use-after-free bug in the TIOCNOTTY handler

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.

Published: 2026-04-22 Last update: 2026-05-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-5398 is rated Low Risk (35.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.02%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-5398

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-22 — 0.02% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-5398

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.4 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.5 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-5398

GitHub Security Advisory for CVE-2026-5398

GHSA-w9v4-7vpf-w2r4 · Severity: high — The implementation of TIOCNOTTY failed to clear a back-pointer from the structure representing...

Affected software / configurations for CVE-2026-5398

Vendor Product Version Raw CPE
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:-:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:beta3:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p1:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p10:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p11:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p2:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p3:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p4:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p5:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p6:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p7:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p8:*:*:*:*:*:*
freebsd freebsd 13.5 cpe:2.3:o:freebsd:freebsd:13.5:p9:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:*
freebsd freebsd 14.3 cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*
freebsd freebsd 14.4 cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:*
freebsd freebsd 15.0 cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:*

References for CVE-2026-5398

cvelogic Threat Intelligence