VulnerabilityDeferred
CVE-2026-109705
Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component.
CRITICAL 9.6EPSS 0.31%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.31%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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, Thunderbird 153.5, and Firefox ESR 115.44.
- CVSS 3.1
- 9.6 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- EPSS
- 0.31% probability · 24th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Source
- security@mozilla.org
EPSS moved from 0.3% on 14 October 2026 to 0.3% on 27 October 2026.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2040905
- https://www.mozilla.org/security/advisories/mfsa2026-106/
- https://www.mozilla.org/security/advisories/mfsa2026-108/
- https://www.mozilla.org/security/advisories/mfsa2026-109/
- https://www.mozilla.org/security/advisories/mfsa2026-110/
- https://www.mozilla.org/security/advisories/mfsa2026-119/
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.