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CVE-2021-23991

6.8 · MEDIUM

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…

Published Jun 24, 2021EPSS 1.03%

Overview

CVE-2021-23991 is a medium-severity vulnerability. It was published on June 24, 2021 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbugzilla.mozilla.org/show_bug.cgi?id=1673240Refwww.mozilla.org/security/advisories/mfsa2021-13/Refbugzilla.mozilla.org/show_bug.cgi?id=1673240Refwww.mozilla.org/security/advisories/mfsa2021-13/

How CyberStrike helps

Frequently asked questions

What is CVE-2021-23991?

CVE-2021-23991 is a medium-severity vulnerability. It was published on June 24, 2021 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2021-23991?

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-23991?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-23991?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-23991 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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