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Vulnerability · Published Aug 20, 2026 · Assigned by GitHub_M

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

Medium 6.5

In plain English

A medium-severity information exposure in mailpit from axllent. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.2%top 87.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/axllent/mailpit1.30.6GHSA-8r62-w5wh-fc5m
Gogithub.com/axllent/mailpit1.30.6GO-2026-6271

Affected products (as reported)

VendorProductVersions
axllent mailpit >= 1.29.0, < 1.30.6

Weakness: CWE-177, CWE-200, CWE-346 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

References