CVE-2018-12391: Mozilla Firefox

High severity, CVSS 8.8. EPSS: 2.1% chance of exploitation in the next 30 days.

During HTTP Live Stream playback on Firefox for Android, audio data can be accessed across origins in violation of security policies. Because the problem is in the underlying Android service, this issue is addressed by treating all HLS streams as cross-origin and opaque to access. *Note: this issue only affects Firefox for Android. Desktop versions of Firefox are unaffected.*. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.

Affected products

• Mozilla Firefox: before 63.0 (fixed in 63.0)
• Mozilla Firefox ESR: before 60.3 (fixed in 60.3)
• Mozilla Thunderbird: before 60.3 (fixed in 60.3)

Published 2019-02-28. Last modified 2026-06-17.