CVE-2025-6435

Summary

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.

Impact & exploitability

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

Affected products we track (1)

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Additional information

• NVD record
• https://www.mozilla.org/security/advisories/mfsa2025-51/Advisory
• https://www.mozilla.org/security/advisories/mfsa2025-54/Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=1950056
• https://bugzilla.mozilla.org/show_bug.cgi?id=1961777