github.com/mattermost/mattermost/server/public vulnerable to path traversal in API route construction

Exploitation

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

CVSS

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

EPSS

• CVE-2026-13426: 0.29% estimated exploitation activity in the next 30 days; percentile 21.72 (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.

The Mattermost Go module github.com/mattermost/mattermost/server/public versions < v0.1.22 fail to validate path parameters when constructing API route paths which allows an attacker to redirect API calls to unintended endpoints via crafted IDs containing path traversal components. Mattermost Advisory ID: MMSA-2025-00532

Published by the source

26 Jun 2026, 15:32 UTC

Last modified by the source

3 Nov 2026, 22:15 UTC

Source last checked

4 Nov 2026, 06:30 UTC

1. Revision 2 · amended · 4 Nov 2026

   Amended from osv record GHSA-72v2-v53v-4qmm

2. Revision 1 · created · 3 Nov 2026

   Published from ghsa record GHSA-72v2-v53v-4qmm

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# Patch Next advisory brief: CVE-2026-13426

Advisory: github.com/mattermost/mattermost/server/public vulnerable to path traversal in API route construction
IDs: CVE-2026-13426, GHSA-72v2-v53v-4qmm
Record: https://patchnext.com/advisories/cve-2026-13426 (revision 2, source checked 4 Nov 2026, 06:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/mattermost/mattermost/server/public 0.1.22. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost/server/public: affected < 0.1.22; fixed in 0.1.22

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost/server/public: 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/mattermost/mattermost/server/public.
- 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-72v2-v53v-4qmm (GitHub-reviewed advisory GHSA-72v2-v53v-4qmm lists affected ranges: Go github.com/mattermost/mattermost/server/public >=0 <0.1.22)
- Verified: https://osv.dev/vulnerability/GHSA-72v2-v53v-4qmm (OSV record GHSA-72v2-v53v-4qmm lists affected ranges: Go github.com/mattermost/mattermost/server/public >=0 <0.1.22 (fixed))

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