CVE-2020-6820

State: Published
Severity: 8.1 High
Published: Apr 24, 2020
Updated: Oct 21, 2025
Reserved: Jan 10, 2020

Description

Under certain conditions, when handling a ReadableStream, 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.

Scores

CVSS	Score	Vector	Source
3.1	8.1 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Affected Products

Product	Versions
ThunderbirdMozilla	before 68.7.0Affected
FirefoxMozilla	before 74.0.1Affected
Firefox ESRMozilla	before 68.6.1Affected

References

https://www.mozilla.org/security/advisories/mfsa2020-14/
https://www.mozilla.org/security/advisories/mfsa2020-11/
https://bugzilla.mozilla.org/show_bug.cgi?id=1626728
USN-4335-1vendor-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-6820government-resource

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