CVE-2023-4581: Undefined Security Weakness

Excel .xll add-in files did not have a blocklist entry in Firefox's executable blocklist which allowed them to be downloaded without any warning of their potential harm. This vulnerability affects Firefox 117, Firefox ESR 102.15, Firefox ESR 115.2, Thunderbird 102.15, and Thunderbird 115.2...

Mozilla: XLL file extensions were downloadable without warnings

The Mozilla Foundation Security Advisory describes this flaw as: Excel .xll add-in files did not have a blocklist entry in Firefox's executable blocklist which allowed them to be downloaded without any warning of their potential harm...