Axllent Mailpit up to 1.30.3 Thumbnail thumbnails.go imaging.Decode resource consumption

Summaryinfo

A vulnerability marked as problematic has been reported in Axllent Mailpit up to 1.30.3. Affected is the function imaging.Decode of the file server/apiv1/thumbnails.go of the component Thumbnail Handler. The manipulation leads to resource consumption. This vulnerability is uniquely identified as CVE-2026-67446. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Axllent Mailpit up to 1.30.3. This issue affects the function imaging.Decode of the file server/apiv1/thumbnails.go of the component Thumbnail Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to 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. Impacted is availability. The summary by CVE is:

Mailpit is an email testing tool and API for developers. Prior to 1.30.4, Mailpit decodes attacker-supplied image attachments into a full raster before checking decoded dimensions, pixel count, or memory use in the GET /api/v1/message/{id}/part/{partID}/thumb endpoint. The Thumbnail handler in server/apiv1/thumbnails.go obtains attachment bytes through storage.GetAttachmentPart(), accepts image/* content, and calls imaging.Decode() with AutoOrientation before imaging.Fill() scales the image to 180 by 120 pixels. A compact image declaring very large dimensions can therefore consume disproportionately large memory and CPU, and opening the message UI can trigger the same endpoint through server/ui-src/components/message/MessageAttachments.vue. This can degrade availability when an unauthenticated client can store the crafted attachment and reach the web API. This issue is fixed in version 1.30.4.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-67446 since 07/29/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 1.30.4 eliminates this vulnerability.

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Productinfo

Vendor

• Axllent

Name

• Mailpit

Version

• 1.30.0
• 1.30.1
• 1.30.2
• 1.30.3

Website

• Product: https://github.com/axllent/mailpit/

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