What’s Vulnerable › Vulnerabilities

CVE-2026-67448: Mailpit: WebSocket origin check bypass via percent-encoded path (regression of CVE-2026-22689)

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-18
• Weakness: CWE-177

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.

Affected products

• axllent mailpit: from 1.29.0, < 1.30.6

References

• https://github.com/axllent/mailpit/commit/fbe5e006c3f1682b819df58b4a932d7a84920be9
• https://github.com/axllent/mailpit/releases/tag/v1.30.6
• https://github.com/axllent/mailpit/security/advisories/GHSA-8r62-w5wh-fc5m

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