Mattermost doesn't sanitize sensitive configuration fields in the Mattermost Calls plugin

Exploitation

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

CVSS

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

EPSS

• CVE-2026-6347: 0.27% estimated exploitation activity in the next 30 days; percentile 18.62 (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 in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the plaintext values present in the exported plugin configuration.. Mattermost Advisory ID: MMSA-2026-00605

Published by the source

18 May 2026, 09:31 UTC

Last modified by the source

1 Jun 2026, 15:44 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-82j6-4fq7-fx62

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# Patch Next advisory brief: CVE-2026-6347

Advisory: Mattermost doesn't sanitize sensitive configuration fields in the Mattermost Calls plugin
IDs: CVE-2026-6347, GHSA-82j6-4fq7-fx62
Record: https://patchnext.com/advisories/cve-2026-6347 (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 7.6)
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-plugin-calls 1.12.0-rc2; github.com/mattermost/mattermost-server 11.5.2, 11.4.4, 10.11.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost-plugin-calls: affected < 1.12.0-rc2; fixed in 1.12.0-rc2
- Go github.com/mattermost/mattermost-server: affected >= 11.5.0, < 11.5.2; >= 10.11.0, < 10.11.14; >= 11.4.0, < 11.4.4; fixed in 11.4.4, 10.11.14, 11.5.2

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost-plugin-calls: 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-plugin-calls, 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-82j6-4fq7-fx62 (GitHub-reviewed advisory GHSA-82j6-4fq7-fx62 lists affected ranges: Go github.com/mattermost/mattermost-server >=11.5.0 =10.11.0 =11.4.0 =0 <1.12.0-rc2)

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