CVE-2021-29953: Mozilla Firefox

Medium severity, CVSS 6.1. EPSS: 0.6% chance of exploitation in the next 30 days.

A malicious webpage could have forced a Firefox for Android user into executing attacker-controlled JavaScript in the context of another domain, resulting in a Universal Cross-Site Scripting vulnerability. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected. Further details are being temporarily withheld to allow users an opportunity to update.*. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

Affected products

• Mozilla Firefox: before 88.0.1 (fixed in 88.0.1); before 88.1.3 (fixed in 88.1.3)

Published 2021-06-24. Last modified 2026-06-17.