Mattermost doesn't sanitize sensitive configuration fields before including them in support packet generation

Exploitation

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

CVSS

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

EPSS

• CVE-2026-6346: 0.30% estimated exploitation activity in the next 30 days; percentile 22.89 (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.

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in plaintext via downloading a support packet from the System Console.. Mattermost Advisory ID: MMSA-2026-00607

Published by the source

18 May 2026, 09:31 UTC

Last modified by the source

1 Jun 2026, 15:41 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9p64-jpc7-m2rp

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# Patch Next advisory brief: CVE-2026-6346

Advisory: Mattermost doesn't sanitize sensitive configuration fields before including them in support packet generation
IDs: CVE-2026-6346, GHSA-9p64-jpc7-m2rp
Record: https://patchnext.com/advisories/cve-2026-6346 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
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/v8 11.5.2, 11.4.4, 10.11.14, 8.0.0-20260326202606-fac92f4a71f3; github.com/mattermost/mattermost-server 5.3.2-0.20260326202606-fac92f4a71f3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost/server/v8: affected >= 11.5.0, < 11.5.2; >= 10.11.0, < 10.11.14; >= 11.4.0, < 11.4.4; < 8.0.0-20260326202606-fac92f4a71f3; fixed in 8.0.0-20260326202606-fac92f4a71f3, 11.4.4, 10.11.14, 11.5.2
- Go github.com/mattermost/mattermost-server: affected < 5.3.2-0.20260326202606-fac92f4a71f3; fixed in 5.3.2-0.20260326202606-fac92f4a71f3

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost/server/v8: check the installed version with your package manager.
- Go github.com/mattermost/mattermost-server: 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/v8, github.com/mattermost/mattermost-server.
- 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-9p64-jpc7-m2rp (GitHub-reviewed advisory GHSA-9p64-jpc7-m2rp lists affected ranges: Go github.com/mattermost/mattermost/server/v8 >=11.5.0 =10.11.0 =11.4.0 =0 =0 <5.3.2-0.20260326202606-fac92f4a71f3)

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