CVE-2021-29975: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 1% chance of exploitation in the next 30 days.

Through a series of DOM manipulations, a message, over which the attacker had control of the text but not HTML or formatting, could be overlaid on top of another domain (with the new domain correctly shown in the address bar) resulting in possible user confusion. This vulnerability affects Firefox < 90.

Affected products

• Mozilla Firefox: before 90.0 (fixed in 90.0)

Published 2021-08-05. Last modified 2026-06-17.