CVE-2021-4221

Public Exploit

Description

If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. <br>*This bug only affects Firefox for Android. Other operating systems are unaffected.*<br>*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox < 92.

Category

4.3
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.63%
Vendor Advisory mozilla.org Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Published at:
Updated at:

References

Link Tags
https://www.mozilla.org/security/advisories/mfsa2021-38/ vendor advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1704422 issue tracking exploit vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-4221?
CVE-2021-4221 has been scored as a medium severity vulnerability.
How to fix CVE-2021-4221?
To fix CVE-2021-4221, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-4221 being actively exploited in the wild?
It is possible that CVE-2021-4221 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-4221?
CVE-2021-4221 affects Mozilla Firefox.
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.