CVE-2020-6819
Actively exploited. CVE-2020-6819 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Mozilla Firefox and Thunderbird contain a race condition vulnerability when running the nsDocShell destructor under certain conditions. The race condition creates a use-after-free vulnerability, causing unspecified impacts.
CSIRTS triage
- What
- A race condition vulnerability creates a use-after-free condition, leading to unspecified impacts.
- Who is affected
- Users of Mozilla Firefox and Thunderbird are affected by this vulnerability.
- Urgency
- Immediate remediation is necessary due to the critical nature of the vulnerability and successful exploitation being possible.
- Action
- Update to the latest versions of Firefox and Thunderbird.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 86% of all EPSS-scored CVEs.
Advisory coverage (1)
- criticalexploitedCVE-2020-6819: Mozilla Firefox And Thunderbird Use-After-Free Vulnerabilitycisa-kev · 2021-11-03
External references
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