Multiple vulnerabilities in Dovecot

1) Resource management error

EUVDB-ID: #VU54284

Risk: Medium

CVSSv3.1: 5.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-28200

CWE-ID: CWE-399 - Resource Management Errors

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper management of internal resources within regex sieve extension. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Dovecot: 1.2.0 - 2.3.14

External links

http://dovecot.org/pipermail/dovecot-news/2021-June/000460.html

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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

2) Path traversal

EUVDB-ID: #VU54285

Risk: Low

CVSSv3.1: 2.9 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-29157

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Exploit availability: No

Description

The vulnerability allows a local user to perform directory traversal attacks.

The vulnerability exists due to validation of kid and azp fields in JWT tokens. A local user to ability to control a JWT token location can login as any MTA user and access their emails.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Dovecot: 2.3.11 - 2.3.14

External links

http://dovecot.org/pipermail/dovecot-news/2021-June/000461.html

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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

3) Code injection

EUVDB-ID: #VU54286

Risk: Medium

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

CVE-ID: CVE-2021-33515

CWE-ID: CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists in the way STARTTLS command in processed by the SMTP server. the commands sent during the session before the STARTTLS command are queued and executed later, after the STARTTLS finished with the client. As a result, a remote attacker can perform a MitM attack and gain access to victim's emails.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Dovecot: 2.3.0 - 2.3.14

External links

http://dovecot.org/pipermail/dovecot-news/2021-June/000462.html

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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