CVE-2023-4581: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Firefox: before 117.0 (fixed in 117.0); from 115.0, before 115.2 (fixed in 115.2)
• Mozilla Firefox ESR: before 102.15 (fixed in 102.15)
• Mozilla Thunderbird: before 115.2 (fixed in 115.2)

Published 2023-09-11. Last modified 2026-06-17.