# CVE-2020-6819

Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.

- Page: https://www.vulneraibility.com/cve/CVE-2020-6819
- CVSS: 8.1
- Known exploited: yes, in CISA KEV since 2021-11-03; CISA due date 2022-05-03
- EPSS: 3.04% (percentile 87.7)
- CISA SSVC: exploitation active, automatable no, technical impact total (assessed 2025-02-07)
- Weakness: CWE-416
- Published: 2020-04-24

## Affected versions

- Mozilla Firefox: affected < 74.0.1
- Mozilla Firefox ESR: affected < 68.6.1
- Mozilla Thunderbird: affected < 68.7.0

A version outside these ranges is not a statement that it is unaffected.

## References

- [other] https://www.mozilla.org/security/advisories/mfsa2020-14/
- [other] https://www.mozilla.org/security/advisories/mfsa2020-11/
- [other] https://bugzilla.mozilla.org/show_bug.cgi?id=1620818
- [advisory] https://usn.ubuntu.com/4335-1/
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-6819

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.