CVE-2026-100818CWE-416

CVE-2026-100818

Critical · published September 29, 2026

CVSS v3.1
9.6
EPSS
0%
Percentile
16.7
In the wild
Unconfirmed
What it is

Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

The record
Technical detail
CVSS v3.1
9.6 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00260 · 16.7th percentile
Weakness
CWE-416 · Use After Free
Published
2026-09-29T17:17Z
Affected products (6)
ProductVersionsFixed in
mozilla/firefox< 140.17.0140.17.0
mozilla/firefox≥ 141.0, < 153.4.0153.4.0
mozilla/firefox≥ 154.0.0, < 157.0.0157.0.0
mozilla/thunderbird< 140.17.0140.17.0
mozilla/thunderbird≥ 141.0, < 153.4.0153.4.0
mozilla/thunderbird≥ 154.0, < 157.0157.0
References (7)
https://bugzilla.mozilla.org/show_bug.cgi?id=2069399 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-100/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-101/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-102/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-103/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-97/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-99/ · [email protected]
EPSS history
Timeline
  • 01 OCT 03:44Z
    EPSS moved — → 0%
    epss
  • 29 SEP 12:36Z
    Sandbox escape due to use-after-free in the Widget: Gtk component
    cvelistv5