stalwartlabs stalwart up to 0.13.3 IMAP Protocol Parser resource consumption

Summaryinfo

A vulnerability was found in stalwartlabs stalwart up to 0.13.3. It has been rated as problematic. Affected is an unknown function of the component IMAP Protocol Parser. This manipulation causes resource consumption. The identification of this vulnerability is CVE-2025-61600. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic was found in stalwartlabs stalwart up to 0.13.3. Affected by this vulnerability is an unknown function of the component IMAP Protocol Parser. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

Stalwart is a mail and collaboration server. Versions 0.13.3 and below contain an unbounded memory allocation vulnerability in the IMAP protocol parser which allows remote attackers to exhaust server memory, potentially triggering the system's out-of-memory (OOM) killer and causing a denial of service. The CommandParser implementation enforces size limits on its dynamic buffer in most parsing states, but several state handlers omit these validation checks. This issue is fixed in version 0.13.4. A workaround for this issue is to implement rate limiting and connection monitoring at the network level, however this does not provide complete protection.

The advisory is shared at github.com. This vulnerability is known as CVE-2025-61600 since 09/26/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 0.13.4 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch a8e631e881bded8128358732f18e02ca94a4e677 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• stalwartlabs

Name

• stalwart

Version

• 0.13.0
• 0.13.1
• 0.13.2
• 0.13.3

License

• open-source

Website

• Product: https://github.com/stalwartlabs/stalwart/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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