Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-controlled message IDs

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L

EPSS

• CVE-2026-45711: 0.39% estimated exploitation activity in the next 30 days; percentile 33.13 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The mailpit dump --http <base-url <out-dir sub-command downloads every message from a remote Mailpit instance and writes each one as <id.eml inside the user-supplied output directory. The message ID field is taken verbatim from the JSON response of the remote server and concatenated into the output path with path.Join, which silently normalizes .. segments. A malicious HTTP server impersonating Mailpit can therefore make mailpit dump write attacker-controlled bytes to any path the running user can write, fully outside the intended output directory. Details Anyone who can convince a user to run mailpit dump --http <attacker-url <dir (typosquat, phishing tutorial, MITM of a plain-http:// Mailpit, or a compromised internal Mailpit they back up regularly) obtains an arbitrary file write primitive as the dumping user. Realistic post-exploitation includes overwriting init/cron files, shell startup files, CI artifact upload targets, web roots, etc. — anything the dumping user can…

Published by the source

19 May 2026, 15:53 UTC

Last modified by the source

2 Sep 2026, 23:39 UTC

Source last checked

26 Oct 2026, 15:28 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-qx5x-85p8-vg4j

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# Patch Next advisory brief: CVE-2026-45711

Advisory: Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-controlled message IDs
IDs: CVE-2026-45711, GHSA-qx5x-85p8-vg4j
Record: https://patchnext.com/advisories/cve-2026-45711 (revision 1, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/axllent/mailpit 1.30.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/axllent/mailpit: affected < 1.30.0; fixed in 1.30.0

## Suggested inspection (read-only)
- Go github.com/axllent/mailpit: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/axllent/mailpit.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-qx5x-85p8-vg4j (GitHub-reviewed advisory GHSA-qx5x-85p8-vg4j lists affected ranges: Go github.com/axllent/mailpit >=0 <1.30.0)

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