CVE-2023-25729: Mozilla Firefox

High severity, CVSS 8.8. EPSS: 0.7% chance of exploitation in the next 30 days.

Permission prompts for opening external schemes were only shown for <code>ContentPrincipals</code> resulting in extensions being able to open them without user interaction via <code>ExpandedPrincipals</code>. This could lead to further malicious actions such as downloading files or interacting with software already installed on the system. This vulnerability affects Firefox < 110, Thunderbird < 102.8, and Firefox ESR < 102.8.

Affected products

• Mozilla Firefox: before 110.0 (fixed in 110.0)
• Mozilla Firefox ESR: before 102.8 (fixed in 102.8)
• Mozilla Thunderbird: before 102.8 (fixed in 102.8)

Published 2023-06-02. Last modified 2026-06-17.