CVE-2021-29964

Mozilla: Out of bounds-read when parsing a `WM_COPYDATA` message

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Severity

Moderate

Red Hat Product Security

7.1

CVSS 3.1

Review impact separately from score.

Published · June 1, 2021

Updated · November 22, 2025

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.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 7.1
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

CWE-125 · Out-of-bounds Read