Mattermost doesn't validate user channel membership when attaching Mattermost posts as comments to Jira issues

Exploitation

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

CVSS

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

EPSS

• CVE-2025-13767: 0.19% estimated exploitation activity in the next 30 days; percentile 9.17 (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 11.1.x <= 11.1.0, 11.0.x <= 11.0.5, 10.12.x <= 10.12.3, 10.11.x <= 10.11.7 fails to validate user channel membership when attaching Mattermost posts as comments to Jira issues, which allows an authenticated attacker with access to the Jira plugin to read post content and attachments from channels they do not have access to.

Published by the source

24 Dec 2025, 09:30 UTC

Last modified by the source

27 Feb 2026, 22:04 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fmqf-pmcm-8cx9

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# Patch Next advisory brief: CVE-2025-13767

Advisory: Mattermost doesn't validate user channel membership when attaching Mattermost posts as comments to Jira issues
IDs: CVE-2025-13767, GHSA-fmqf-pmcm-8cx9
Record: https://patchnext.com/advisories/cve-2025-13767 (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 4.3)
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 8.0.0-20251121122154-b57c297c6d7; github.com/mattermost/mattermost-server 11.1.1, 11.0.6, 10.12.4, 10.11.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost/server/v8: affected < 8.0.0-20251121122154-b57c297c6d7; fixed in 8.0.0-20251121122154-b57c297c6d7
- Go github.com/mattermost/mattermost-server: affected >= 10.11.0, < 10.11.8; >= 10.12.0, < 10.12.4; >= 11.0.0, < 11.0.6; >= 11.1.0, < 11.1.1; fixed in 10.11.8, 10.12.4, 11.0.6, 11.1.1

## 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-fmqf-pmcm-8cx9 (GitHub-reviewed advisory GHSA-fmqf-pmcm-8cx9 lists affected ranges: Go github.com/mattermost/mattermost/server/v8 >=0 =10.11.0 =10.12.0 =11.0.0 =11.1.0 <11.1.1)

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