GHSA-jf5h-xfw4-p8gp is a low-severity (CVSS 3) CWE-1287 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 GitHub Plugin Bot Identity Validation Bypass Allows Arbitrary GitHub Reaction Injection
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-jf5h-xfw4-p8gp 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 379,145 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🐹github.com/mattermost/mattermost🐹github.com/mattermost/mattermost-plugin-githubReal-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 10.11.x <= 10.11.6 and Mattermost GitHub plugin versions <=2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 10.11.0-rc1&&< 10.11.7-0.20251106103514-3b05384dd014 | 10.11.7-0.20251106103514-3b05384dd014go get github.com/mattermost/mattermost/server/v8@v10.11.7-0.20251106103514-3b05384dd014 |
| 🐹Go | github.com/mattermost/mattermost | all versions | 10.11.7-0.20251106103514-3b05384dd014go get github.com/mattermost/mattermost@v10.11.7-0.20251106103514-3b05384dd014 |
| 🐹Go | github.com/mattermost/mattermost | ≥ 11.0.0-alpha.1&&< 11.1.0 | 11.1.0go get github.com/mattermost/mattermost@v11.1.0 |
| 🐹Go | github.com/mattermost/mattermost-plugin-github | all versions | 1.0.1-0.20250829075715-0deffcfc6beego get github.com/mattermost/mattermost-plugin-github@v1.0.1-0.20250829075715-0deffcfc6bee |
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 10.11.7-0.20251106103514-3b05384dd014 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jf5h-xfw4-p8gp 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-jf5h-xfw4-p8gp can be triaged on real exposure rather than presence alone.
Tailored to GHSA-jf5h-xfw4-p8gp. 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-jf5h-xfw4-p8gp in your dependencies?
O3 Security finds GHSA-jf5h-xfw4-p8gp across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.