Mattermost doesn't verify that post actions invoking `/share-issue-publicly` were created by the Jira pluginGHSA-vww6-79rv-3j4x
MEDIUMFix: mattermost/mattermost#34551GHSA-vww6-79rv-3j4x is a medium-severity (CVSS 4.1) CWE-863 vulnerability in github.com/mattermost/mattermost/server/v8. A fix is available for github.com/mattermost/mattermost/server/v8 — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-vww6-79rv-3j4x.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-serverReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | all versions | 8.0.0-20251121122154-b57c297c6d7go get github.com/mattermost/mattermost/server/v8@v8.0.0-20251121122154-b57c297c6d7 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.11.0&&< 10.11.8 | 10.11.8go get github.com/mattermost/mattermost-server@v10.11.8 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.12.0&&< 10.12.4 | 10.12.4go get github.com/mattermost/mattermost-server@v10.12.4 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 11.0.0&&< 11.0.6 | 11.0.6go get github.com/mattermost/mattermost-server@v11.0.6 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 11.1.0&&< 11.1.1 | 11.1.1go get github.com/mattermost/mattermost-server@v11.1.1 |
Affected Products
mattermost servermattermostDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost/server/v8, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20251121122154-b57c297c6d7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vww6-79rv-3j4x is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-vww6-79rv-3j4x in your dependencies?
Find it across Go, including transitive dependencies.