CVE-2023-5727: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.9% chance of exploitation in the next 30 days.

The executable file warning was not presented when downloading .msix, .msixbundle, .appx, and .appxbundle files, which can run commands on a user's computer. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 119, Firefox ESR < 115.4, and Thunderbird < 115.4.1.

Affected products

• Mozilla Firefox: before 119.0 (fixed in 119.0)
• Mozilla Firefox ESR: before 115.4 (fixed in 115.4)
• Mozilla Thunderbird: before 115.4.1 (fixed in 115.4.1)

Published 2023-10-25. Last modified 2026-06-17.