What is CVE-2026-109765?

CVE-2026-109765 is a medium-severity vulnerability, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 4.2/10. Published 2026-10-13.

How severe is CVE-2026-109765?

Medium severity. CVSS v3 base score is 4.2 out of 10.

CVE-2026-109765

CVE-2026-109765

Race condition, use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Vulnerability class: Race Condition

Published 2026-10-13 · last modified 2026-10-13.

CVSS v3 metric

CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Weakness classification (CWE)

CWE-362 — Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)
CWE-416 — Use After Free

References

bugzilla.mozilla.org/show_bug.cgi
www.mozilla.org/security/advisories/mfsa2026-106/
www.mozilla.org/security/advisories/mfsa2026-108/
www.mozilla.org/security/advisories/mfsa2026-109/
www.mozilla.org/security/advisories/mfsa2026-110/

Frequently asked questions

What is CVE-2026-109765?: CVE-2026-109765 is a medium-severity vulnerability, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 4.2/10. Published 2026-10-13.
How severe is CVE-2026-109765?: Medium severity. CVSS v3 base score is 4.2 out of 10.