CVE-2021-43533: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 0.6% chance of exploitation in the next 30 days.

When parsing internationalized domain names, high bits of the characters in the URLs were sometimes stripped, resulting in inconsistencies that could lead to user confusion or attacks such as phishing. This vulnerability affects Firefox < 94.

Affected products

• Mozilla Firefox: before 94.0 (fixed in 94.0)

Published 2021-12-08. Last modified 2026-06-17.