Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.
History

Tue, 10 Sep 2024 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
Vendors & Products Redhat enterprise Linux

Tue, 10 Sep 2024 20:30:00 +0000


Tue, 10 Sep 2024 14:45:00 +0000

Type Values Removed Values Added
Description A security issue was found in Dovecot. Very large headers can lead to resource exhaustion when parsing messages. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to the message-header-parser, it starts building up a "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit so large headers can cause large memory usage. This issue occurs whether it is a single long header line or a single header split into multiple lines. Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Mon, 09 Sep 2024 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.2
Vendors & Products Redhat
Redhat rhel Eus

Thu, 22 Aug 2024 14:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H'}

threat_severity

Moderate


Wed, 21 Aug 2024 19:00:00 +0000

Type Values Removed Values Added
Description No description is available for this CVE. A security issue was found in Dovecot. Very large headers can lead to resource exhaustion when parsing messages. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to the message-header-parser, it starts building up a "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit so large headers can cause large memory usage. This issue occurs whether it is a single long header line or a single header split into multiple lines.

Tue, 20 Aug 2024 21:30:00 +0000

Type Values Removed Values Added
Description No description is available for this CVE.
Title dovecot: very large headers can cause resource exhaustion when parsing message
Weaknesses CWE-770
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important


cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published: 2024-09-10T14:38:50.523Z

Updated: 2024-09-10T19:19:51.788Z

Reserved: 2024-01-12T07:03:12.862Z

Link: CVE-2024-23185

cve-icon Vulnrichment

Updated: 2024-09-10T15:02:59.227Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-09-10T15:15:14.967

Modified: 2024-09-10T15:50:47.237

Link: CVE-2024-23185

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-08-15T00:00:00Z

Links: CVE-2024-23185 - Bugzilla