axllent mailpit up to 1.28.1 missing origin validation in websockets

Summaryinfo

A vulnerability classified as problematic has been found in axllent mailpit up to 1.28.1. The affected element is an unknown function. This manipulation causes missing origin validation in websockets. This vulnerability appears as CVE-2026-22689. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in axllent mailpit up to 1.28.1. It has been declared as problematic. Affected by this vulnerability is some unknown processing. The manipulation with an unknown input leads to a missing origin validation in websockets vulnerability. The CWE definition for the vulnerability is CWE-1385. The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid. As an impact it is known to affect confidentiality. The summary by CVE is:

Mailpit is an email testing tool and API for developers. Prior to version 1.28.2, the Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability. An attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time. This issue has been patched in version 1.28.2.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-22689 since 01/08/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 1.28.2 eliminates this vulnerability. Applying the patch 6f1f4f34c98989fd873261018fb73830b30aec3f 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.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-1872). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• axllent

Name

• mailpit

Version

• 1.28.0
• 1.28.1

License

• open-source

Website

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

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CPE 2.2info

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Be aware that VulDB is the high quality source for vulnerability data.

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