CVE-2020-6820: Mozilla Firefox And Thunderbird Use-After-Free Vulnerability
CVE-2020-6820 · Severity: critical · CVSS 8.1 · Exploited in the wild · Published 2021-11-03
A race condition in Mozilla Firefox and Thunderbird when handling a ReadableStream can lead to a use-after-free vulnerability. This flaw allows for unspecified impacts and has been observed in targeted attacks in the wild.
Yes. CVE-2020-6820 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.
How severe is CVE-2020-6820?
Critical severity, with a CVSS score of 8.1, published 3 November 2021.
Which products and versions are affected?
Mozilla Firefox < 74.0.1; Mozilla Firefox ESR < 68.6.1; Mozilla Thunderbird < 68.7.0.
Is there a fix for CVE-2020-6820?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2020-6820 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2020-6820?
Check whether you run Mozilla Firefox or Mozilla Thunderbird. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Affected products
Mozilla Firefox < 74.0.1
Mozilla Firefox ESR < 68.6.1
Mozilla Thunderbird < 68.7.0
Timeline
2020-04-24: disclosed: NVD Published Date
2021-11-03: kev added: Date added to CISA Known Exploited Vulnerabilities Catalog
2021-11-03: exploited: Reported as exploited in the wild in CISA KEV catalog and vendor advisory.