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

> Attackers can bypass WebSocket origin checks via percent-encoded paths to read live email metadata from unauthenticated Mailpit instances.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 20 Aug 2026
- **Updated:** 21 Aug 2026
- **Also known as:** GHSA-8r62-w5wh-fc5m, GO-2026-6271

## What is CVE-2026-67448?

CVE-2026-67448 is a medium-severity vulnerability in axllent mailpit, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### 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.

Weakness: CWE-346 (Origin Validation Error), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), CWE-177 (Improper Handling of URL Encoding (Hex Encoding))

## Which versions are affected by CVE-2026-67448?

3 open source packages ship an affected version, including github.com/axllent/mailpit.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/axllent/mailpit` | Go | From 1.29.0 | 1.30.6 |
| `github.com/axllent/mailpit` | Go | From 1.29.0 | 1.30.6 |
| `github.com/axllent/mailpit` | Go | From 1.29.0 | 1.30.6 |

## How do I fix CVE-2026-67448?

Upgrade github.com/axllent/mailpit to 1.30.6 or later.

## Is CVE-2026-67448 being exploited?

There is no known exploitation of CVE-2026-67448 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67448 and fix it if it is affected.

What it is: CVE-2026-67448 is a medium-severity vulnerability in axllent mailpit, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-67448 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/axllent/mailpit (Go): affected from 1.29.0; fixed in 1.30.6
- github.com/axllent/mailpit (Go): affected from 1.29.0; fixed in 1.30.6
- github.com/axllent/mailpit (Go): affected from 1.29.0; fixed in 1.30.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-67448/ (Markdown: https://insights.sbomify.com/CVE-2026-67448/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67448
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67448
- OSV: https://osv.dev/vulnerability/CVE-2026-67448

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67448/
Summaries are generated and may contain mistakes; the official description above is the record.