What’s Vulnerable › Vulnerabilities

CVE-2021-4127

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-12-22 · updated 2026-06-17

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An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited.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

Affected products

• Mozilla Firefox ESR: before 78.9.0 — fixed in 78.9.0
• Mozilla Thunderbird: before 78.9.0 — fixed in 78.9.0

How to fix

Upgrade to a fixed version: Mozilla Firefox ESR 78.9.0; Mozilla Thunderbird 78.9.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1691547
• https://www.mozilla.org/security/advisories/mfsa2021-11/
• https://www.mozilla.org/security/advisories/mfsa2021-12/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1691547
• https://www.mozilla.org/security/advisories/mfsa2021-11/
• https://www.mozilla.org/security/advisories/mfsa2021-12/

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