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.
Affected products
mozilla: firefox; mozilla: thunderbird
References4
- www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2025-54/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=1950056 Permissions Required
- bugzilla.mozilla.org/show_bug.cgi?id=1961777 Permissions Required
Metrics
- CVSS 3.1
-
8.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 40 · as of 7 November 2026
- CWE
- CWE-434
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