CVE-2025-9072 is a high-severity (CVSS 7.6) Open Redirect vulnerability in github.com/mattermost/mattermost-server. A fix is available for github.com/mattermost/mattermost-server — see the affected versions and patch details below.
One-Click Mattermost Account Takeover via Poisoned RelayState SAML Parameter
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2025-9072.
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🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹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 10.10.x <= 10.10.1, 10.5.x <= 10.5.9, 10.9.x <= 10.9.4 fail to validate the redirect_to parameter, allowing an attacker to craft a malicious link that, once a user authenticates with their SAML provider, could post the user’s cookies to an attacker-controlled URL.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.10.0&&< 10.10.2 | 10.10.2go get github.com/mattermost/mattermost-server@v10.10.2 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.5.0&&< 10.5.10 | 10.5.10go get github.com/mattermost/mattermost-server@v10.5.10 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.9.0&&< 10.9.5 | 10.9.5go get github.com/mattermost/mattermost-server@v10.9.5 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | all versions | 8.0.0-20250731063404-9eebaadf8f72go get github.com/mattermost/mattermost/server/v8@v8.0.0-20250731063404-9eebaadf8f72 |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost-server to 10.10.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-9072 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Frequently Asked Questions
Is CVE-2025-9072 in your dependencies?
Find it across Go, including transitive dependencies.