GHSA-63f2-6959-2pxj — v6
MEDIUMGHSA-63f2-6959-2pxj is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in github.com/mattermost/mattermost-server/v6. A fix is available for github.com/mattermost/mattermost-server/v6 — see the affected versions and patch details below.
Mattermost vulnerable to cross-site scripting (XSS)
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 GHSA-63f2-6959-2pxj.
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-63f2-6959-2pxj 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/v6🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹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
Boards in Mattermost allows an attacker to upload a malicious SVG image file as an attachment to a card and share it using a direct link to the file.
Issue Identifier: MMSA-2023-00139
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost-server/v6 | ≥ 6.0.0&&< 7.1.6 | 7.1.6go get github.com/mattermost/mattermost-server/v6@v7.1.6 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 7.7.0&&< 7.7.2 | 7.7.2go get github.com/mattermost/mattermost-server@v7.7.2 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 7.1.0&&< 7.1.6 | 7.1.6go get github.com/mattermost/mattermost-server@v7.1.6 |
| 🐹Go | github.com/mattermost/mattermost-server | ≥ 7.8.0&&< 7.8.1 | 7.8.1go get github.com/mattermost/mattermost-server@v7.8.1 |
| 🐹Go | github.com/mattermost/mattermost-server/v5 | ≥ 5.0.0&&< 7.1.6 | 7.1.6go get github.com/mattermost/mattermost-server/v5@v7.1.6 |
| 🐹Go | github.com/mattermost/mattermost-server/v6 | ≥ 3.3.0&&< 7.1.6 | 7.1.6go get github.com/mattermost/mattermost-server/v6@v7.1.6 |
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/v6, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost-server/v6 to 7.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-63f2-6959-2pxj 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-63f2-6959-2pxj can be triaged on real exposure rather than presence alone.
Tailored to GHSA-63f2-6959-2pxj. 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-63f2-6959-2pxj in your dependencies?
O3 Security finds GHSA-63f2-6959-2pxj across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.