Denial of service in Dovecot

Published: 2019-04-18 | Updated: 2019-04-18
Severity Medium
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2019-10691
Exploitation vector Network
Public exploit N/A
Vulnerable software Dovecot Subscribe
Vendor Dovecot

Security Advisory

This security advisory describes one medium risk vulnerability.

1) Input validation error

Severity: Medium

CVSSv3: 6.5 [CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C] [PCI]

CVE-ID: CVE-2019-10691

CWE-ID: CWE-20 - Improper Input Validation


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

The vulnerability exists due to improper input validation of user-supplied characters in UTF-8 encoding within the JSON encoder. A remote unauthenticated attacker can supply a specially crafted string that contains invalid UTF-8 characters via a username during authentication process or via “From” or “Subject” headers in an email (if OX push notification driver is enabled) and crash the affected server.

Successful exploitation of the vulnerability will result in denial of service (DoS) attack.


Install updates from vendor's website.

Vulnerable software versions

Dovecot: 2.3.0,, 2.3.1, 2.3.2,, 2.3.3, 2.3.4,, 2.3.5,

CPE External links

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.