CVE-2021-4127
CVE-2021-4127 is a critical-severity vulnerability in Mozilla Firefox Esr with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- EPSS exploit prediction: 1% (55th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Mozilla Firefox Esr
- Published:
- Last modified:
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An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited.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.
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- An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited.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 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-4127 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-4127?
- CVE-2021-4127 primarily affects Mozilla Firefox Esr. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-4127?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2021-4127 published?
- CVE-2021-4127 was published on 2022-12-22 and last updated on 2026-06-17.
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/
Affected products (2)
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
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