If a user downloaded a file lacking an extension on Windows, and then "Open"-ed it from the downloads panel, if there was an executable file in the downloads directory with the same name but with an executable extension (such as .bat or .exe) that executable would have been launched instead. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.
https://bugzilla.mozilla.org/show_bug.cgi?id=1661365
https://www.mozilla.org/security/advisories/mfsa2020-54/
Source: MITRE
Published: 2021-01-07
Updated: 2021-01-12
Type: NVD-CWE-noinfo
Base Score: 6.8
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 8.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 2.8
Severity: HIGH