Vulnerability identifier: #VU54829

Vulnerability risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-29969

CWE-ID: CWE-77

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 execute arbitrary commands.

The vulnerability exists in the way Thunderbird handles IMAP server responses sent prior to STARTTLS process. A remote attacker with ability to perform MitM attack can send arbitrary IMAP commands before the STARTTLS handshake and execute them after the handshake is complete.

This could have resulted in Thunderbird showing incorrect information, for example the attacker could have tricked Thunderbird to show folders that didn't exist on the IMAP server.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Thunderbird: 78.0 - 78.11.0, 68.0 - 68.12.1, 60.0 - 60.9.1

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-30/

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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.