CVE-2020-12389: Mozilla Firefox

Critical severity, CVSS 10.0. EPSS: 1.7% chance of exploitation in the next 30 days.

The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.

Affected products

• Mozilla Firefox: before 76.0 (fixed in 76.0)
• Mozilla Firefox ESR: before 68.8.0 (fixed in 68.8.0)

Published 2020-05-26. Last modified 2026-06-17.