CVE-2024-40886 — v8
MEDIUMCVE-2024-40886 is a medium-severity (CVSS 4.6) Cross-Site Request Forgery (CSRF) 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.
One-click Client-Side Path Traversal Leading to CSRF in User Management admin page
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 CVE-2024-40886.
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
CVE-2024-40886 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/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8Real-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 9.9.x <= 9.9.1, 9.5.x <= 9.5.7, 9.10.x <= 9.10.0, 9.8.x <= 9.8.2 fail to sanitize user inputs in the frontend that are used for redirection which allows for a one-click client-side path traversal that is leading to CSRF in User Management page of the system console.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 9.9.0&&< 9.9.2 | 9.9.2go get github.com/mattermost/mattermost/server/v8@v9.9.2 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 9.5.0&&< 9.5.8 | 9.5.8go get github.com/mattermost/mattermost/server/v8@v9.5.8 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 9.10.0&&< 9.10.1 | 9.10.1go get github.com/mattermost/mattermost/server/v8@v9.10.1 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 9.8.0&&< 9.8.3 | 9.8.3go get github.com/mattermost/mattermost/server/v8@v9.8.3 |
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 9.9.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-40886 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-40886 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-40886. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-40886 in your dependencies?
O3 Security finds CVE-2024-40886 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.