Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 140.0 |
| Mozilla | Thunderbird | < 140.0 |
Related Weaknesses (CWE)
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
FAQ
What is CVE-2025-6435?
CVE-2025-6435 is a vulnerability with a CVSS score of 8.1 (HIGH). 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 use...
How severe is CVE-2025-6435?
CVE-2025-6435 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-6435?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.