CVE-2020-6819

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

CVE-2020-6819 is fixed in 10 products on 2 platforms, first by firefox 74.0.1+build1-0ubuntu0.18.04.1, released April 2, 2020. It is being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on November 3, 2021. Patch Radar priority: Patch now.

Patch nowCISA KEVFixed on 2 platforms
CVSS
8.8
Critical
Exploitation
Exploited
Reported by the vendor
CISA KEV
Nov 3, 2021
Federal due date May 3, 2022
EPSS
0.0304
87th percentile

Under certain conditions, when running the nsDocShell destructor, 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.

Where it's fixed

ProductFixed inFixReleased
Windows apps
Mozilla Firefox ESR (en-US) 78.0esr Mozilla Firefox ESR (en-US) 78.0esr Jun 25, 2020
Linux
firefox · RHEL 8 0:68.6.1-1.el8_1 RHSA-2020:1341 Apr 7, 2020
firefox · Ubuntu 18.04.6 LTS (bionic) 74.0.1+build1-0ubuntu0.18.04.1 firefox 74.0.1+build1-0ubuntu0.18.04.1 Apr 2, 2020
firefox · Ubuntu 20.04 LTS (focal) 75.0+build3-0ubuntu1 firefox 75.0+build3-0ubuntu1 Apr 6, 2020
firefox · ol 8 0:68.6.1-1.0.1.el8_1 ELSA-2020-1341 Apr 9, 2020
firefox-geckodriver · Ubuntu 18.04.6 LTS (bionic) 74.0.1+build1-0ubuntu0.18.04.1 firefox-geckodriver 74.0.1+build1-0ubuntu0.18.04.1 Apr 2, 2020
firefox-geckodriver · Ubuntu 20.04 LTS (focal) 75.0+build3-0ubuntu1 firefox-geckodriver 75.0+build3-0ubuntu1 Apr 6, 2020
firefox-mozsymbols · Ubuntu 18.04.6 LTS (bionic) 74.0.1+build1-0ubuntu0.18.04.1 firefox-mozsymbols 74.0.1+build1-0ubuntu0.18.04.1 Apr 2, 2020
firefox-mozsymbols · Ubuntu 20.04 LTS (focal) 75.0+build3-0ubuntu1 firefox-mozsymbols 75.0+build3-0ubuntu1 Apr 6, 2020
thunderbird · RHEL 8 0:68.7.0-1.el8_1 RHSA-2020:1495 Apr 16, 2020
thunderbird · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 thunderbird 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
thunderbird · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 thunderbird 1:68.7.0+build1-0ubuntu1 Apr 6, 2020
thunderbird · ol 8 0:68.7.0-1.0.1.el8_1 ELSA-2020-1495 Apr 18, 2020
thunderbird-gnome-support · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 thunderbird-gnome-support 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
thunderbird-gnome-support · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 thunderbird-gnome-support 1:68.7.0+build1-0ubuntu1 Apr 6, 2020
thunderbird-mozsymbols · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 thunderbird-mozsymbols 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
thunderbird-mozsymbols · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 thunderbird-mozsymbols 1:68.7.0+build1-0ubuntu1 Apr 6, 2020
xul-ext-calendar-timezones · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 xul-ext-calendar-timezones 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
xul-ext-calendar-timezones · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 xul-ext-calendar-timezones 1:68.7.0+build1-0ubuntu1 Apr 6, 2020
xul-ext-gdata-provider · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 xul-ext-gdata-provider 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
xul-ext-gdata-provider · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 xul-ext-gdata-provider 1:68.7.0+build1-0ubuntu1 Apr 6, 2020
xul-ext-lightning · Ubuntu 18.04.6 LTS (bionic) 1:68.7.0+build1-0ubuntu0.18.04.1 xul-ext-lightning 1:68.7.0+build1-0ubuntu0.18.04.1 Apr 6, 2020
xul-ext-lightning · Ubuntu 20.04 LTS (focal) 1:68.7.0+build1-0ubuntu1 xul-ext-lightning 1:68.7.0+build1-0ubuntu1 Apr 6, 2020

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