CVE-2026-67448

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

MEDIUM
6.5
CVSS Score
Published: August 20, 2026 at 09:29 PM UTC
Updated: October 18, 2026 at 08:10 PM UTC
1 product affected across 1 vendorMailpit

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Affected range stops below 1.30.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-177CWE-200CWE-346

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