Vulnerability · Published Jun 24, 2021 · Assigned by mozilla

CVE-2021-23993

Medium 6.5

In plain English

A medium-severity security flaw in Thunderbird from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)6.5Medium

Exploit odds (30 days)0.4%top 63.2% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	thunderbird	1:78.10.0-1	DEBIAN-CVE-2021-23993
Debian:13	thunderbird	1:78.10.0-1	DEBIAN-CVE-2021-23993
Debian:14	thunderbird	1:78.10.0-1	DEBIAN-CVE-2021-23993

Affected products (as reported)

Vendor	Product	Versions
Mozilla	Thunderbird	unspecified – before 78.9.1

References

https://www.mozilla.org/security/advisories/mfsa2021-13/ x_refsource_MISC
https://bugzilla.mozilla.org/show_bug.cgi?id=1666360 x_refsource_MISC