CVE-2023-46254 is a medium-severity (CVSS 4.3) Information Exposure vulnerability in github.com/projectcapsule/capsule. A fix is available for github.com/projectcapsule/capsule — see the affected versions and patch details below.
Service accounts can see namespaces of other tenants in capsule-proxy
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-2023-46254 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/projectcapsule/capsule🐹github.com/projectcapsule/capsule-proxyReal-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
capsule-proxy is a reverse proxy for Capsule kubernetes multi-tenancy framework. A bug in the RoleBinding reflector used by capsule-proxy gives ServiceAccount tenant owners the right to list Namespaces of other tenants backed by the same owner kind and name. For example consider two tenants solar and wind. Tenant solar, owned by a ServiceAccount named tenant-owner in the Namespace solar. Tenant wind, owned by a ServiceAccount named tenant-owner in the Namespace wind. The Tenant owner solar would be able to list the namespaces of the Tenant wind and vice-versa, although this is not correct. The bug introduces an exfiltration vulnerability since allows the listing of Namespace resources of other Tenants, although just in some specific conditions: 1. capsule-proxy runs with the --disable-caching=false (default value: false) and 2. Tenant owners are ServiceAccount, with the same resource name, but in different Namespaces. This vulnerability doesn't allow any privilege escalation on the outer tenant Namespace-scoped resources, since the Kubernetes RBAC is enforcing this. This issue has been addressed in version 0.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/projectcapsule/capsule | all versions | 0.4.5go get github.com/projectcapsule/capsule@v0.4.5 |
| 🐹Go | github.com/projectcapsule/capsule-proxy | all versions | 0.4.5go get github.com/projectcapsule/capsule-proxy@v0.4.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/projectcapsule/capsule, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/projectcapsule/capsule to 0.4.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46254 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-2023-46254 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-46254. 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-2023-46254 in your dependencies?
O3 Security finds CVE-2023-46254 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.