Name: CVE-2026-109778: Improper Privilege Management
Creator: Rapid7
Published: 2026-10-13T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-109778, CWE-269, CVSS 8.8, EPSS 0.0028

Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

CVSS Details

CVSS 3.1 Base Score: 8.8
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Mfsa2026 106	—	Upgrade to Mozilla Firefox version 158.0Upgrade to the latest version of Mozilla Firefox	Oct 13, 2026	Oct 13, 2026
Mfsa2026 108	—	Upgrade to Mozilla Firefox ESR version 153.5Upgrade to the latest version of Mozilla Firefox	Oct 13, 2026	Oct 13, 2026
Mozilla Thunderbird	—	Upgrade to the latest version of Mozilla ThunderbirdUpgrade to Mozilla Thunderbird version 153.5	Oct 13, 2026	Oct 13, 2026

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CVSS Details

Covered by Rapid7

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