CVE-2021-29951

MEDIUM
6.5
CVSS Score
Published: June 24, 2021 at 01:18 PM UTC
Updated: June 17, 2026 at 03:48 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR· also runs on 1 platform

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Severity
MEDIUM6.5
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 87
Affected range stops below 87, so it looks safe — our inference, not a vendor statement
Affected range stops below 87.0, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)
v < 78.10.1
Affected range stops below 78.10.1, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)
v < 78.10.1
Affected range stops below 78.10.1, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

References (4)

x_refsource_MISCIssue TrackingVendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1690062
x_refsource_MISCRelease NotesVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-10/
x_refsource_MISCRelease NotesVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-18/
x_refsource_MISCRelease NotesVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-19/

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-269

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