CVE-2025-6435

HighCVSS 8.1/10Last modified Sep 30, 2026

Description

If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

Metrics

CVSS 3.1 8.1/10CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-434

Affected software

Vendor	Product	Versions
Mozilla	Firefox	—
Mozilla	Thunderbird	—

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1950056Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=1961777Permissions Required
https://www.mozilla.org/security/advisories/mfsa2025-51/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-54/Vendor Advisory

Timeline

Published: Jun 24, 2025
Last modified: Sep 30, 2026
NVD status: Modified

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