CVE-2026-22689: axllent mailpit Missing Origin Validation in WebSockets

Vulnerability summary

CVE-2026-22689 is a medium (CVSS 6.5) Missing Origin Validation in WebSockets vulnerability in axllent mailpit. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-01-2026
   PublishedVulnerability first disclosed.
2. 12-01-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-1385Missing Origin Validation in WebSocketsThe product uses a WebSocket, but it does not properly verify that the source of data or communication is valid.