Unrated severityCISA KEVNVD Advisory· Published Apr 24, 2020· Updated Oct 21, 2025

CVE-2020-6820

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.

Affected products

Mozilla Corporation/Firefoxv5
Range: unspecified
Mozilla Corporation/Thunderbirdv5
Range: unspecified
Mozilla/Firefox ESRv5
Range: unspecified

Patches

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

usn.ubuntu.com/4335-1/mitrevendor-advisoryx_refsource_UBUNTU
bugzilla.mozilla.org/show_bug.cgimitrex_refsource_MISC
www.mozilla.org/security/advisories/mfsa2020-11/mitrex_refsource_MISC
www.mozilla.org/security/advisories/mfsa2020-14/mitrex_refsource_MISC

News mentions

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epss	0.003
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kev	0.120
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ransomware	0.000