CVE-2026-15687 in Java Client
Summary
by MITRE • 07/23/2026
A security issue was discovered in the Kubernetes Java client library where a compromised pod may be able to create new files in arbitrary locations on the client machine executing copy operations via non-tar copyDirectoryFromPod when enableTarCompressing is false.
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Analysis
by VulDB Data Team • 07/23/2026
This vulnerability exists within the Kubernetes Java client library and represents a significant security flaw that could allow privilege escalation through malicious pod manipulation. The issue specifically affects the copyDirectoryFromPod functionality when the enableTarCompressing parameter is set to false, creating a path traversal condition that enables unauthorized file creation in arbitrary locations on the host system. The vulnerability stems from insufficient input validation and sanitization of directory paths during file copy operations between pods and client machines.
The technical implementation flaw occurs when the Java client processes directory copies without proper path validation, allowing malicious actors to manipulate directory structures through specially crafted file names or symbolic links. This weakness falls under the Common Weakness Enumeration category CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. When enableTarCompressing is disabled, the client library bypasses certain security checks that would normally prevent malicious path manipulation during archive operations.
The operational impact of this vulnerability extends beyond simple unauthorized file creation, potentially enabling attackers to overwrite critical system files, inject malicious code into the host environment, or establish persistent backdoors through compromised pods. Attackers could leverage this flaw to escalate privileges from pod-level access to full host system compromise, particularly in environments where Kubernetes clusters are deployed with elevated permissions for client applications. The vulnerability is especially concerning in multi-tenant environments or when client machines lack proper file system restrictions and monitoring.
Mitigation strategies should focus on immediate parameter configuration changes, specifically ensuring that enableTarCompressing is set to true whenever copy operations occur, which activates the necessary security controls within the library. Organizations should implement comprehensive network segmentation and pod security policies that restrict unnecessary file system access from pods to client machines. Additionally, regular security audits of Kubernetes client libraries and their configurations should be conducted to identify similar path traversal vulnerabilities across other components. The vulnerability aligns with ATT&CK technique T1059 which covers command and scripting interpreter, as it could enable attackers to execute arbitrary commands through file manipulation on the host system, and T1566 which addresses malicious file execution through compromised systems.