Vulnerability identifier: #VU52003

Vulnerability risk: Medium

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23993

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Thunderbird
Client/Desktop applications / Messaging software

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to disable sending of encrypted messages.

The vulnerability exists due to insufficient validation of imported OpenPGP keys. A remote attacker can force the victim to import a specially crafted OpenPGO key with a subkey that has an invalid self signature and prevent users from sending encrypted messages to a correspondent.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 78.0 - 78.9.0, 68.0 - 68.12.1, 60.0 - 60.9.1

---

External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-13/

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.