GHSA-mxxc-p822-2hx9 is a high-severity (CVSS 8.1) CWE-441 vulnerability in github.com/zalando/skipper. A fix is available for github.com/zalando/skipper — see the affected versions and patch details below.
Skipper Ingress Controller Allows Unauthorized Access to Internal Services via ExternalName
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-mxxc-p822-2hx9.
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-mxxc-p822-2hx9 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/zalando/skipperReal-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
Impact
When running Skipper as an Ingress controller, users with permissions to create an Ingress and a Service of type ExternalName can create routes that enable them to use Skipper's network access to reach internal services.
Patches
https://github.com/zalando/skipper/releases/tag/v0.24.0 disables Kubernetes ExternalName by default.
Workarounds
Developers can allow list targets of an ExternalName by using -kubernetes-only-allowed-external-names=true and allow list via regular expressions -kubernetes-allowed-external-name '^[a-z][a-z0-9-.]+[.].allowed.example$'
References
https://kubernetes.io/docs/concepts/services-networking/service/#externalname
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/zalando/skipper | all versions | 0.24.0go get github.com/zalando/skipper@v0.24.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zalando/skipper, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zalando/skipper to 0.24.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mxxc-p822-2hx9 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-mxxc-p822-2hx9 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-mxxc-p822-2hx9. 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-mxxc-p822-2hx9 in your dependencies?
O3 Security finds GHSA-mxxc-p822-2hx9 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.