CVE-2021-29951

mediumpriority · track · 27EPSS 0.019 · 79 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.85% (79th) EPSS

CVSS 6.4 · medium

Is it mine?

11 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-28

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

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.06.4mediumAV:N/AC:L/Au:N/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 10 · impact 4.9

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 2.5

v3.16.5mediumAV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Nsecondary · FSTEC (BDU) RU

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-269USprimaryCWE-269US

affected products (11)

Products and version ranges known to be affected.

Mozilla Firefoxunspecified → 87enisa_euvdEU
Mozilla Firefox ESRunspecified → 78.10.1enisa_euvdEU
Mozilla Thunderbirdunspecified → 78.10.1enisa_euvdEU
Microsoft Corp Windowsall versionsfstec_bduRU
Mozilla Corp. Firefox≤ 87fstec_bduRU
Mozilla Corp. Firefox ESR≤ 78.10.1fstec_bduRU
Mozilla Corp. Thunderbird≤ 78.10.1fstec_bduRU
АО «ИВК» Альт 8 СПall versionsfstec_bduRU
mozilla firefox< 87.0nvdUScpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
mozilla firefox esr< 78.10.1nvdUScpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
mozilla thunderbird< 78.10.1nvdUScpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2021-06-24modified 2026-06-17

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+6661 more

references (19)

External citations — patches, advisories, analysis.

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