CVE-2025-47283: Gardener Privilege Escalation Vulnerability

CVE-2025-47283 Overview

A critical privilege escalation vulnerability has been discovered in Gardener, the automated management and operation platform for Kubernetes clusters as a service. This security flaw allows a user with administrative privileges for a Gardener project to obtain control over the seed cluster(s) where their shoot clusters are managed. The vulnerability affects the gardener/gardener (gardenlet) component and impacts all Gardener installations regardless of the public cloud provider(s) used for seed or shoot clusters.

Critical Impact

A malicious project administrator could escalate privileges to gain full control over seed clusters, potentially compromising all shoot clusters managed by those seeds and enabling lateral movement across the entire Gardener infrastructure.

Affected Products

• Gardener versions prior to 1.116.4
• Gardener versions prior to 1.117.5
• Gardener versions prior to 1.118.2
• Gardener versions prior to 1.119.0

Discovery Timeline

• 2025-05-19 - CVE-2025-47283 published to NVD
• 2026-02-06 - Last updated in NVD database

Technical Details for CVE-2025-47283

Vulnerability Analysis

This privilege escalation vulnerability stems from improper input validation (CWE-20) within the gardenlet component of Gardener. The flaw enables users who already possess administrative privileges within a Gardener project to break out of their intended access boundaries and gain unauthorized control over seed clusters.

In Gardener's architecture, seed clusters are the management clusters that host the control planes for user workload clusters (called shoot clusters). The separation between project-level administrative access and seed-level access is a critical security boundary. This vulnerability effectively bypasses that boundary, allowing project administrators to elevate their privileges beyond the intended scope.

The attack can be executed over the network without user interaction, and the vulnerability has scope change implications—meaning a successful exploit affects resources beyond the vulnerable component's security scope.

Root Cause

The root cause is improper input validation (CWE-20) in the gardenlet component. The gardenlet failed to adequately validate or restrict certain operations that could be performed by project administrators, allowing them to manipulate configurations or resources in ways that grant access to underlying seed cluster infrastructure.

Attack Vector

The attack is network-based and requires the attacker to have low privileges (specifically, administrative access to a Gardener project). The exploitation path involves:

1. Attacker obtains or already possesses project administrator privileges within a Gardener installation
2. Attacker leverages the improper input validation flaw in gardenlet to craft malicious requests or configurations
3. Through the vulnerability, the attacker escalates privileges to gain control over the seed cluster(s) managing their shoot clusters
4. With seed cluster access, the attacker could potentially compromise other shoot clusters managed by the same seed, access secrets, or perform lateral movement

The vulnerability mechanism involves the gardenlet's handling of project administrator requests. Due to insufficient validation, certain operations allow the attacker to influence seed cluster resources beyond their intended scope. For detailed technical information, refer to the GitHub Security Advisory GHSA-3hw7-qj9h-r835.

Detection Methods for CVE-2025-47283

Indicators of Compromise

• Unexpected API calls or configuration changes originating from project administrators targeting seed cluster resources
• Anomalous gardenlet logs showing unusual resource access patterns or privilege escalation attempts
• Unauthorized access to seed cluster credentials or kubeconfig files
• Unexpected pods, services, or deployments appearing in seed cluster namespaces

Detection Strategies

• Implement audit logging for all gardenlet operations and monitor for unusual patterns from project administrator accounts
• Deploy network segmentation monitoring to detect unexpected cross-boundary communication between shoot and seed clusters
• Enable Kubernetes audit policies to capture API server events that indicate privilege escalation attempts
• Correlate RBAC changes with expected operational baselines to identify unauthorized permission modifications

Monitoring Recommendations

• Monitor gardenlet component logs for errors or warnings related to authentication, authorization, or input validation
• Set up alerts for any direct access attempts to seed cluster resources from project-level service accounts
• Implement continuous monitoring of Gardener version deployments to ensure patched versions are running
• Review project administrator activity logs for any deviations from normal operational patterns

How to Mitigate CVE-2025-47283

Immediate Actions Required

• Upgrade Gardener to a patched version immediately: 1.116.4, 1.117.5, 1.118.2, or 1.119.0 depending on your current version branch
• Audit all project administrator accounts and their recent activities for signs of exploitation
• Review access controls and implement additional network policies to restrict project-to-seed cluster communication
• Rotate any credentials that may have been exposed if exploitation is suspected

Patch Information

The Gardener project has released security patches addressing this vulnerability. Organizations should upgrade to one of the following fixed versions based on their current deployment:

• Version 1.116.4 - View Patch Commit
• Version 1.117.5 - View Patch Commit
• Version 1.118.2 - View Patch Commit
• Version 1.119.0 - View Patch Commit

For complete details, see the GitHub Security Advisory GHSA-3hw7-qj9h-r835.

Workarounds

• Restrict project administrator privileges to only trusted users until patches can be applied
• Implement network policies to limit communication between shoot cluster control planes and seed cluster infrastructure
• Enable enhanced audit logging on all gardenlet operations to detect potential exploitation attempts
• Consider temporarily suspending new shoot cluster provisioning if immediate patching is not possible

# Example: Verify Gardener version and upgrade
# Check current gardenlet version
kubectl get deployment gardenlet -n garden -o jsonpath='{.spec.template.spec.containers[0].image}'

# Upgrade to patched version (adjust version as appropriate for your branch)
# Follow your organization's standard Gardener upgrade procedures
# Refer to official Gardener documentation for version-specific upgrade steps