Vulnerability · Published Jun 24, 2021 · Assigned by mozilla

CVE-2021-23991

Medium 6.8

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 1.0% (higher than 64% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)6.8Medium

Exploit odds (30 days)1.0%top 36.0% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

If a Thunderbird user has previously imported Alice's OpenPGP key, and Alice has extended the validity period of her key, but Alice's updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice's key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. 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-2021-23991
Debian:13	thunderbird	1:78.10.0-1	DEBIAN-CVE-2021-23991
Debian:14	thunderbird	1:78.10.0-1	DEBIAN-CVE-2021-23991

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=1673240 x_refsource_MISC