Executive brief
A security flaw exists in the Kubernetes Java client library, which is used by developers to interact with Kubernetes clusters. If an administrator uses this library to copy files from a compromised or malicious container (pod), the container could trick the administrator's computer into creating files in unintended locations. This could potentially lead to system instability or unauthorized file placement on the machine running the Java application.
Technical details
A path traversal vulnerability (CWE-22) exists in the Kubernetes Java client library's `copyDirectoryFromPod` method. When the `enableTarCompressing` parameter is set to `false` (often done for distroless containers), the library fails to properly validate file paths sent from the pod. A compromised pod can exploit this during a copy operation to create files in arbitrary locations on the client machine. The attack requires the client to initiate a copy operation from a pod controlled by the attacker and requires high privileges (PR:H) and user interaction (UI:R). The issue is fixed in versions 25.0.1, 26.0.1, and 27.0.0.
Affected products
- Kubernetes java-client >= 10.0.0, < 25.0.1; 26.0.0
Timeline
- 2026-07-22: disclosed: Issue reported on GitHub
- 2026-07-23: advisory: CVE published to NVD