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CVE-2021-29964

HIGH
7.1
CVSS Score
Published: June 24, 2021 at 01:15 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
HIGH7.1
Exploit prediction
EPSS 0.8%

Description

A locally-installed hostile program could send `WM_COPYDATA` messages that Firefox would process incorrectly, leading to an out-of-bounds read. *This bug only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 78.11, Firefox < 89, and Firefox ESR < 78.11.

Affected

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

Firefox· Mozilla
95%
v < 89
Affected range stops below 89, so it looks safe — our inference, not a vendor statement
Affected range stops below 89.0, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)
Firefox ESR· Mozilla
95%
v < 78.11
Affected range stops below 78.11, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)
Thunderbird· Mozilla
95%
v < 78.11
Affected range stops below 78.11, 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_MISCPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1706501
x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-23/
x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-24/
x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-26/

CVSS

7.1HIGH[email protected]
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-125

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