Is CVE-2021-4127 actively exploited?

No active exploitation of CVE-2021-4127 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-4127 be exploited remotely?

Yes. CVE-2021-4127 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-4127?

CVE-2021-4127 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-4127

CRITICAL

CVE-2021-4127

NVD-CWE-noinfoPublished: December 22, 2022· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited.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.

NVD Source

Risk Analysis

The use of an outdated graphics library (Angle) introduces vulnerabilities that could be exploited to compromise the system. The critical severity rating highlights the importance of keeping third-party dependencies updated.

No public exploit is known, and it is not in the KEV catalog. The flaw is remotely exploitable.

Recommended Action

Update to Firefox ESR 78.9 or Thunderbird 78.9 to replace the vulnerable graphics library.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2021-4127 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.