#VU17374 Authentication bypass in Dovecot - CVE-2019-3814

Vulnerability identifier: #VU17374

Vulnerability risk: Medium

CVSSv4.0: 7.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:P/U:Green]

CVE-ID: CVE-2019-3814

CWE-ID: CWE-592

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Dovecot
Server applications / Mail servers

Vendor: Dovecot

Description
The vulnerability allows a remote authenticated attacker to bypass authentication.

The weakness exists due to taking of the username from the user provided authentication fields (e.g. LOGIN command). A remote attacker with access to a valid trusted certificate without the ssl_cert_username_field in it can bypass password verification if the provided trusted SSL certificate is missing the username field and login as anyone else in the system

Mitigation
The vulnerability has been addressed in the versions 2.2.36.1, 2.3.4.1.

Vulnerable software versions

Dovecot: 1.1.0 - 2.3.4

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External links
https://www.dovecot.org/list/dovecot/2019-February/114575.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.