CVE-2021-23993

Thunderbird: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent.

CVE-2021-23993 is fixed in 7 products on 2 platforms, first by RHSA-2021:1193, released April 14, 2021. It is not reported as exploited. Patch Radar priority: Routine.

RoutineFixed on 2 platforms
CVSS
6.5
Moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0042
36th percentile

An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.

Where it's fixed

ProductFixed inFixReleased
Windows apps
Mozilla Thunderbird (en-US) 78.10.0 Mozilla Thunderbird (en-US) 78.10.0 Apr 15, 2021
Linux
thunderbird · RHEL 8 0:78.9.1-1.el8_3 RHSA-2021:1193 Apr 14, 2021
thunderbird · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 thunderbird 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
thunderbird · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 thunderbird 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021
thunderbird · ol 8 0:78.9.1-1.0.1.el8_3 ELSA-2021-1193 Apr 15, 2021
thunderbird-gnome-support · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 thunderbird-gnome-support 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
thunderbird-gnome-support · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 thunderbird-gnome-support 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021
thunderbird-mozsymbols · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 thunderbird-mozsymbols 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
thunderbird-mozsymbols · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 thunderbird-mozsymbols 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021
xul-ext-calendar-timezones · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 xul-ext-calendar-timezones 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
xul-ext-calendar-timezones · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 xul-ext-calendar-timezones 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021
xul-ext-gdata-provider · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 xul-ext-gdata-provider 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
xul-ext-gdata-provider · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 xul-ext-gdata-provider 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021
xul-ext-lightning · Ubuntu 18.04.6 LTS (bionic) 1:78.11.0+build1-0ubuntu0.18.04.2 xul-ext-lightning 1:78.11.0+build1-0ubuntu0.18.04.2 Jun 1, 2021
xul-ext-lightning · Ubuntu 20.04 LTS (focal) 1:78.11.0+build1-0ubuntu0.20.04.2 xul-ext-lightning 1:78.11.0+build1-0ubuntu0.20.04.2 Jun 1, 2021

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