Mailpit is Vulnerable to Server-Side Request Forgery (SSRF) via Link Check API

Exploitation

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

CVSS

5.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

EPSS

• CVE-2026-27808: 0.53% estimated exploitation activity in the next 30 days; percentile 45.03 (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 Link Check API (/api/v1/message/{ID}/link-check) is vulnerable to Server-Side Request Forgery (SSRF). The server performs HTTP HEAD requests to every URL found in an email without validating target hosts or filtering private/internal IP addresses. The response returns status codes and status text per link, making this a non-blind SSRF. In the default configuration (no authentication on SMTP or API), this is fully exploitable remotely with zero user interaction. This is the same class of vulnerability that was fixed in the HTML Check API (CVE-2026-23845 / GHSA-6jxm-fv7w-rw5j) and the screenshot proxy (CVE-2026-21859 / GHSA-8v65-47jx-7mfr), but the Link Check code path was not included in either fix. Details The doHead() function in https://github.com/axllent/mailpit/blob/v1.29.0/internal/linkcheck/status.go#L59-L98 creates a plain http.Transport{} and http.Client with no DialContext hook or IP validation: The call chain is: 1. GET /api/v1/message/{ID}/link-check hits…

Published by the source

26 Feb 2026, 15:18 UTC

Last modified by the source

26 Feb 2026, 15:18 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mpf7-p9x7-96r3

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# Patch Next advisory brief: CVE-2026-27808

Advisory: Mailpit is Vulnerable to Server-Side Request Forgery (SSRF) via Link Check API
IDs: CVE-2026-27808, GHSA-mpf7-p9x7-96r3
Record: https://patchnext.com/advisories/cve-2026-27808 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.8)
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 1.29.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/axllent/mailpit: affected <= 1.29.1; fixed in 1.29.2

## 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-mpf7-p9x7-96r3 (GitHub-reviewed advisory GHSA-mpf7-p9x7-96r3 lists affected ranges: Go github.com/axllent/mailpit >=0 <=1.29.1)

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