CVE-2026-58093: Kernel use-after-free via tty ioctls
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by freebsd, published 2026-08-26).
Weakness: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (‘Race Condition’); CWE-416: Use After Free
How it can be exploited
Exploitable with local access with high attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: no. Technical impact: total.
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-14825, CNVD-2026-40417, EUVD-2026-66250, ZDI-26-784, ZDI-26-838
VEDAS cluster: VEDAS:FRIENDLYFROST
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Research and write-ups (2)
- Research or write-up: https://www.zerodayinitiative.com/advisories/ZDI-26-784
- Research or write-up: https://www.zerodayinitiative.com/advisories/ZDI-26-838
Vulnerability databases and vendor advisories (3)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-66250
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-58093
- Vulnerability database or vendor advisory: https://www.cnvd.org.cn/flaw/show/CNVD-2026-40417
News (1)
3 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.001
low predicted chance of attack - VEDAS
- 0.985
strong exploit evidence - On CISA KEV
- Not listed
- Detection rule
- None yet
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| FreeBSD FreeBSD | from 15.1-RELEASE before p3 from 15.0-RELEASE before p13 from 14.4-RELEASE before p9 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: freebsd freebsd, freebsd_project freebsd.
How to fix it
Fixed versions stated in the CVE record: p3, p13, p9.
Vendor guidance:
- https://security.freebsd.org/advisories/FreeBSD-SA-26:62.tty.asc (vendor-advisory)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Vendor advisories and patches
- https://security.freebsd.org/advisories/FreeBSD-SA-26:62.tty.asc (vendor-advisory)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.