Mailpit is an email testing tool and API for developers. From 1.29.0 until 1.30.6, Mailpit's server/server.go origin middleware checks the raw RequestURI for the /api/ prefix while Go's ServeMux routes using the percent-decoded URL path, and server/websockets/client.go configures websocket.Upgrader.CheckOrigin to return true. A malicious website can request /%61pi/events, skip corsOriginAccessControl(), reach the /api/events WebSocket handler, and receive live message IDs, Message-Id values, sender and recipient fields, subjects, tags, and body snippets from an unauthenticated default Mailpit instance after the user visits the site. This is a regression of the earlier WebSocket origin protection and does not affect deployments protected by --ui-auth-file. This issue is fixed in version 1.30.6.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-8r62-w5wh-fc5m Mailpit: WebSocket origin check bypass via percent-encoded path (regression of CVE-2026-22689)
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 20 Aug 2026 21:45:00 +0000

Type Values Removed Values Added
Description Mailpit is an email testing tool and API for developers. From 1.29.0 until 1.30.6, Mailpit's server/server.go origin middleware checks the raw RequestURI for the /api/ prefix while Go's ServeMux routes using the percent-decoded URL path, and server/websockets/client.go configures websocket.Upgrader.CheckOrigin to return true. A malicious website can request /%61pi/events, skip corsOriginAccessControl(), reach the /api/events WebSocket handler, and receive live message IDs, Message-Id values, sender and recipient fields, subjects, tags, and body snippets from an unauthenticated default Mailpit instance after the user visits the site. This is a regression of the earlier WebSocket origin protection and does not affect deployments protected by --ui-auth-file. This issue is fixed in version 1.30.6.
Title Mailpit: WebSocket origin check bypass via percent-encoded path (regression of CVE-2026-22689)
Weaknesses CWE-177
CWE-200
CWE-346
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-20T21:29:29.682Z

Reserved: 2026-07-29T15:07:24.992Z

Link: CVE-2026-67448

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-20T22:17:56.870

Modified: 2026-08-20T22:17:56.870

Link: CVE-2026-67448

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses