Mattermost doesn't verify that post actions invoking /share-issue-publicly were created by the Jira plugin

Exploitation

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

CVSS

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

EPSS

• CVE-2025-64641: 0.18% estimated exploitation activity in the next 30 days; percentile 6.96 (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 fail to verify that post actions invoking /share-issue-publicly were created by the Jira plugin which allowed a malicious Mattermost user to exfiltrate Jira tickets when victim users interacted with affected posts

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-vww6-79rv-3j4x

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# Patch Next advisory brief: CVE-2025-64641

Advisory: Mattermost doesn't verify that post actions invoking `/share-issue-publicly` were created by the Jira plugin
IDs: CVE-2025-64641, GHSA-vww6-79rv-3j4x
Record: https://patchnext.com/advisories/cve-2025-64641 (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 4.1)
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-vww6-79rv-3j4x (GitHub-reviewed advisory GHSA-vww6-79rv-3j4x 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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