CRITICAL

CVE-2026-109705

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component

CVSS v3

9.6

CRITICAL

EPSS Score

—

exploit probability

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-109705 yet.

Full record on NVD

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, and Thunderbird 153.5.

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Published: 2026-10-13
Last Modified: 2026-10-13

Frequently asked questions

What is CVE-2026-109705?

Is CVE-2026-109705 actively exploited?

Active exploitation of CVE-2026-109705 has not been confirmed.

What is the CVSS score for CVE-2026-109705?

CVE-2026-109705 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

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