GHSA-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.
Mattermost doesn't verify that post actions invoking `/share-issue-publicly` were created by the Jira plugin
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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-vww6-79rv-3j4x plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Detection & 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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-vww6-79rv-3j4x can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vww6-79rv-3j4x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-vww6-79rv-3j4x in your dependencies?
O3 Security finds GHSA-vww6-79rv-3j4x across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.