GHSA-4ff6-858j-r822 is a medium-severity (CVSS 4.3) Server-Side Request Forgery (SSRF) vulnerability in github.com/matrix-org/gomatrixserverlib. A fix is available for github.com/matrix-org/gomatrixserverlib — see the affected versions and patch details below.
Gomatrixserverlib Server-Side Request Forgery (SSRF) on redirects and federation
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 GHSA-4ff6-858j-r822.
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-4ff6-858j-r822 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/matrix-org/gomatrixserverlibReal-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
Gomatrixserverlib is a Go library for matrix federation. Gomatrixserverlib is vulnerable to server-side request forgery, serving content from a private network it can access, under certain conditions. The commit c4f1e01 fixes this issue. Users are advised to upgrade. Users unable to upgrade should use a local firewall to limit the network segments and hosts the service using gomatrixserverlib can access.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/matrix-org/gomatrixserverlib | all versions | 0.0.0-20250116181547-c4f1e01eab0dgo get github.com/matrix-org/gomatrixserverlib@v0.0.0-20250116181547-c4f1e01eab0d |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/matrix-org/gomatrixserverlib, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/matrix-org/gomatrixserverlib to 0.0.0-20250116181547-c4f1e01eab0d or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4ff6-858j-r822 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-4ff6-858j-r822 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-4ff6-858j-r822. 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-4ff6-858j-r822 in your dependencies?
O3 Security finds GHSA-4ff6-858j-r822 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.