CVE-2021-4127

Name: CVE-2021-4127
Creator: NVD / NIST
Published: 2022-12-22T20:15:11.787+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.90%

Last modified Jun 17, 2026

CVE-2021-4127 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited. This vulnerability affects Thunderbird < 78.9 and Firefox ESR < 78.9.. EPSS estimates a 0.90% chance of exploitation in the next 30 days.

Description

An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited. This vulnerability affects Thunderbird < 78.9 and Firefox ESR < 78.9.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.90%

55.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mozilla	Firefox Esr	< 78.9.0
Mozilla	Thunderbird	< 78.9.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1691547Exploit, Issue Tracking, Patch, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-11/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-12/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1691547Exploit, Issue Tracking, Patch, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-11/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-12/Vendor Advisory

Timeline

Published: Dec 22, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4127?

An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited. This vulnerability affects Thunderbird < 78.9 and Firefox ESR < 78.9.

How severe is CVE-2021-4127?

CVE-2021-4127 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4127?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4127?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST