CVE-2021-21661: 
Java vulnerability analysis and mitigation

CVE-2021-21661 (SECURITY-2370) affects the Jenkins Kubernetes CLI Plugin versions 1.10.0 and earlier. The vulnerability was discovered in early 2021 and publicly disclosed on June 10, 2021. The issue exists in the plugin's HTTP endpoints where permission checks were not properly implemented (Jenkins Advisory, OSS Security).

The vulnerability stems from missing permission checks in several HTTP endpoints within the Kubernetes CLI Plugin. The security issue is rated as Medium severity according to CVSS scoring system. The technical flaw allows unauthorized access to credential enumeration functionality that should be restricted (Jenkins Advisory).

The vulnerability allows attackers with Overall/Read permission to enumerate credentials IDs stored in Jenkins. These enumerated credentials IDs could potentially be leveraged as part of a larger attack chain to capture the actual credentials if combined with another vulnerability (Jenkins Advisory, OSS Security).

The vulnerability can be exploited by attackers who have Overall/Read permission in the Jenkins environment. The attack vector requires access to specific HTTP endpoints in the Kubernetes CLI Plugin that lack proper permission checks (Jenkins Advisory).

The vulnerability has been fixed in Kubernetes CLI Plugin version 1.10.1. Users should upgrade to this version or later to receive the security fix. In the patched version, enumeration of credentials IDs requires appropriate permissions, effectively closing the security gap (Jenkins Advisory).