CVE-2021-29951
The Mozilla Maintenance Service granted SERVICE_START access to BUILTIN|Users which, in a domain network, grants normal remote users access to start or stop the service.
Does this matter?
Lower severity and a low EPSS score (1.85%). Track it; it rarely justifies an emergency change on its own.
Description
The Mozilla Maintenance Service granted SERVICE_START access to BUILTIN|Users which, in a domain network, grants normal remote users access to start or stop the service. This could be used to prevent the browser update service from operating (if an attacker spammed the 'Stop' command); but also exposed attack surface in the maintenance service. *Note: This issue only affected Windows operating systems older than Win 10 build 1709. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 78.10.1, Firefox < 87, and Firefox ESR < 78.10.1.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- EPSS
- 1.85% probability · 79th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-269
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1690062Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-10/Release Notes, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-18/Release Notes, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-19/Release Notes, Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1690062Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-10/Release Notes, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-18/Release Notes, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-19/Release Notes, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.