CVE-2026-109705CWE-416

CVE-2026-109705

Critical · published October 13, 2026

CVSS v3.1
9.6
EPSS
0%
Percentile
22.8
In the wild
Unconfirmed
What it is

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

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
0.00311 · 22.8th percentile
Weakness
CWE-416 · Use After Free
Published
2026-10-13T17:17Z
References (5)
https://bugzilla.mozilla.org/show_bug.cgi?id=2040905 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-106/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-108/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-109/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-110/ · [email protected]
EPSS history
Timeline
  • 15 OCT 03:28Z
    EPSS moved — → 0%
    epss
  • 13 OCT 12:29Z
    Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component
    cvelistv5
  • 13 OCT 12:29Z
    Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component
    cvelistv5