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CVE-2021-38505

MEDIUM
6.5
CVSS Score
Published: December 8, 2021 at 09:21 PM UTC
Updated: June 17, 2026 at 04:02 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR· also runs on 1 platform

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Severity
MEDIUM6.5
Exploit prediction
EPSS 1%

Description

Microsoft introduced a new feature in Windows 10 known as Cloud Clipboard which, if enabled, will record data copied to the clipboard to the cloud, and make it available on other computers in certain scenarios. Applications that wish to prevent copied data from being recorded in Cloud History must use specific clipboard formats; and Firefox before versions 94 and ESR 91.3 did not implement them. This could have caused sensitive data to be recorded to a user's Microsoft account. *This bug only affects Firefox for Windows 10+ with Cloud Clipboard enabled. Other operating systems are unaffected.*. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Affected

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

Firefox· Mozilla
95%
v < 94
Affected range stops below 94, so it looks safe — our inference, not a vendor statement
Affected range stops below 94.0, so it looks safe — our inference, not a vendor statement
microsoft-windows-10 (environment)
Firefox ESR· Mozilla
95%
v < 91.3
Affected range stops below 91.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 91.3.0, so it looks safe — our inference, not a vendor statement
microsoft-windows-10 (environment)
Thunderbird· Mozilla
95%
v < 91.3
Affected range stops below 91.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 91.3.0, so it looks safe — our inference, not a vendor statement
microsoft-windows-10 (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 TrackingPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1730194
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-48/
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-49/
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-50/

CVSS

6.5MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-668

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