CVE-2025-6435

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.

Score

CVSS 3.1 8.1 High

Status

Modified - security@mozilla.org

Published

2025-06-24

Last modified

2026-04-13

Weaknesses

CWE-434

Affected products

• Firefox (Mozilla)
• Thunderbird (Mozilla)

References

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