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.
References (4)
Core 4
Core References
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=1950056
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=1961777
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-51/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-54/
Scores
CVSS v3
8.1
EPSS
0.0050
EPSS Percentile
66.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
total
Details
CWE
CWE-434
Status
published
Products (4)
mozilla/firefox
< 140.0
Mozilla/Firefox
140
mozilla/thunderbird
< 140.0
Mozilla/Thunderbird
140
Published
Jun 24, 2025
Tracked Since
Feb 18, 2026