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CVE-2020-6820

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

Mozilla Firefox and ThunderbirdApplications & CMS
Open in ThreatlineRecord JSON
CVSS
8.1High
ExploitationExploited in the wildAdded to KEV 3 Nov 2021CISA KEV
Exploit odds (EPSS)7.06%Chance of exploitation activity in the next 30 days, higher than 94% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in68.7.0Also 74.0.1, 68.6.1CVE List
Federal deadline3 May 2022Remediation due date for US federal agenciesCISA KEV
CISA required actionApply updates per vendor instructions. CISA KEV

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 24 Apr 2020, 15:56 UTCPublishedCVE List
  2. 3 Nov 2021Added to CISA KEVCISA KEV

Description

Mozilla Firefox and Thunderbird contain a race condition vulnerability when handling a ReadableStream under certain conditions. The race condition creates a use-after-free vulnerability, causing unspecified impacts.

Text from CVE List

Affected versions 3

  • Thunderbirdaffected: unspecified before 68.7.0CVE List
  • Firefoxaffected: unspecified before 74.0.1CVE List
  • Firefox ESRaffected: unspecified before 68.6.1CVE List

References 6