What’s Vulnerable › Vulnerabilities

CVE-2021-43533

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-12-08 · updated 2026-06-17

Description

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

How to fix

Upgrade to a fixed version: Mozilla Firefox 94.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1724233
• https://www.mozilla.org/security/advisories/mfsa2021-48/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1724233
• https://www.mozilla.org/security/advisories/mfsa2021-48/

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