CVE-2021-23958: Mozilla Firefox

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

The browser could have been confused into transferring a screen sharing state into another tab, which would leak unintended information. This vulnerability affects Firefox < 85.

Affected products

• Mozilla Firefox: before 85.0 (fixed in 85.0)

Published 2021-02-26. Last modified 2026-06-17.