CVE-2025-8023 — mattermost-server
MEDIUMCVE-2025-8023 is a medium-severity (CVSS 6.8) Path Traversal 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.
Path Traversal in Template Upload Allows Uploading Files Outside Target Directory
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-2025-8023.
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-2025-8023 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 377,636 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🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost-server/v5🐹github.com/mattermost/mattermost-server/v6Real-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 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.8.0&&< 10.8.4 | 10.8.4go get github.com/mattermost/mattermost-server@v10.8.4 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.5.0&&< 10.5.9 | 10.5.9go get github.com/mattermost/mattermost-server@v10.5.9 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 9.11.0&&< 9.11.18 | 9.11.18go get github.com/mattermost/mattermost-server@v9.11.18 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 10.9.0&&< 10.9.3 | 10.9.3go get github.com/mattermost/mattermost-server@v10.9.3 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | all versions | 8.0.0-20250708065844-b38e2eccda18go get github.com/mattermost/mattermost/server/v8@v8.0.0-20250708065844-b38e2eccda18 |
| 🐹Go | github.com/mattermost/mattermost-server/v5 | all versions | No fix |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost-server to 10.8.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-8023 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 CVE-2025-8023 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-8023. 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-2025-8023 in your dependencies?
O3 Security finds CVE-2025-8023 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.