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Vulnerability details: VCID-q77k-hc9g-9fhm
Vulnerability ID VCID-q77k-hc9g-9fhm
Aliases CVE-2021-29951
Summary 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.*
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-863 Incorrect Authorization
System Score Found at
cvssv3 6.1 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-29951.json
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
epss 0.00531 https://api.first.org/data/v1/epss?cve=CVE-2021-29951
cvssv3.1 3.3 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
archlinux Medium https://security.archlinux.org/AVG-1914
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-10
generic_textual none https://www.mozilla.org/en-US/security/advisories/mfsa2021-18
generic_textual none https://www.mozilla.org/en-US/security/advisories/mfsa2021-19
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-29951.json
https://api.first.org/data/v1/epss?cve=CVE-2021-29951
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
1961505 https://bugzilla.redhat.com/show_bug.cgi?id=1961505
AVG-1914 https://security.archlinux.org/AVG-1914
mfsa2021-10 https://www.mozilla.org/en-US/security/advisories/mfsa2021-10
mfsa2021-18 https://www.mozilla.org/en-US/security/advisories/mfsa2021-18
mfsa2021-19 https://www.mozilla.org/en-US/security/advisories/mfsa2021-19
No exploits are available.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-29951.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.67198
EPSS Score 0.00531
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T13:17:09.622900+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-18.yml 38.0.0