CVE-2021-41244: Grafana Privilege Escalation Vulnerability

CVE-2021-41244 Overview

Grafana is an open-source platform for monitoring and observability. A critical authorization bypass vulnerability exists in Grafana versions 8.0 through 8.2.3 when the fine-grained access control beta feature is enabled and multiple organizations are configured. This flaw allows Organization Admins to improperly access, list, add, remove, and update user roles in other organizations where they do not have administrative privileges.

Critical Impact

Organization administrators can escalate their privileges across organizational boundaries, gaining unauthorized access to manage users in organizations where they should have no administrative authority, potentially compromising the entire multi-tenant Grafana deployment.

Affected Products

• Grafana versions 8.0 through 8.2.3
• Grafana instances with fine-grained access control beta feature enabled
• Grafana deployments with more than one organization configured

Discovery Timeline

• 2021-11-15 - CVE-2021-41244 published to NVD
• 2021-11-15 - Grafana releases security patch in version 8.2.4
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-41244

Vulnerability Analysis

This vulnerability is classified under CWE-863 (Incorrect Authorization) and CWE-610 (Externally Controlled Reference to a Resource in Another Sphere). When Grafana 8.0 introduced the fine-grained access control mechanism, a design flaw was introduced that failed to properly validate organizational boundaries for administrative actions.

The core issue lies in the authorization logic that permits users holding the Organization Admin role to perform privileged user management operations across organizational boundaries. In a multi-organization Grafana deployment, this breaks the fundamental tenant isolation model, as administrators from one organization can manipulate user accounts and role assignments in completely separate organizations.

The vulnerability requires network access and high-privilege credentials (Organization Admin), but once these prerequisites are met, an attacker gains complete control over user management in all organizations within the Grafana instance, allowing them to modify user privileges, remove legitimate users, or add malicious accounts.

Root Cause

The root cause stems from improper authorization checks in the fine-grained access control feature introduced in Grafana 8.0. The authorization mechanism fails to validate that an Organization Admin's scope of permissions should be limited to their own organization. Instead, the access control logic incorrectly grants cross-organizational administrative capabilities when the fine-grained access control beta feature is active, allowing operations on resources that should be outside the administrator's organizational context.

Attack Vector

The attack is network-based and requires authenticated access with Organization Admin privileges. An attacker who has compromised or legitimately holds an Organization Admin account can exploit this vulnerability by:

1. Authenticating to the Grafana instance with Organization Admin credentials
2. Leveraging the fine-grained access control API endpoints to enumerate organizations
3. Sending API requests to list, add, remove, or modify users in other organizations
4. Establishing persistence by adding malicious accounts or elevating privileges in target organizations

The attack does not require user interaction and can be performed entirely through the Grafana API, making it suitable for automated exploitation once initial access is obtained.

Detection Methods for CVE-2021-41244

Indicators of Compromise

• Unexpected user role changes across multiple organizations in Grafana audit logs
• API calls from Organization Admins targeting user management endpoints for organizations outside their assigned scope
• New user accounts appearing in organizations without corresponding approval workflows
• Anomalous access patterns showing Organization Admins accessing cross-organizational resources

Detection Strategies

• Monitor Grafana API logs for user management operations that span organizational boundaries
• Implement alerting on role modifications, user additions, or removals in organizations where the requesting admin is not authorized
• Review audit logs for sequential enumeration of organizations followed by user management actions
• Cross-reference administrative actions with legitimate change management records

Monitoring Recommendations

• Enable verbose API logging in Grafana to capture all administrative operations with full context
• Deploy SIEM rules to correlate Organization Admin authentication events with cross-organizational API calls
• Implement periodic reviews of user role assignments across all organizations to detect unauthorized changes
• Configure alerts for any user management operations performed outside normal business hours

How to Mitigate CVE-2021-41244

Immediate Actions Required

• Upgrade Grafana to version 8.2.4 or later immediately
• If upgrade is not immediately possible, disable the fine-grained access control feature using the feature flag
• Audit all user accounts and role assignments across organizations for unauthorized changes
• Review recent administrative actions in Grafana logs to identify potential exploitation

Patch Information

Grafana has released version 8.2.4 which addresses this vulnerability. The patch implements proper organizational boundary checks for the fine-grained access control feature. Organizations running Grafana versions 8.0 through 8.2.3 with fine-grained access control enabled should upgrade immediately. For detailed information, refer to the Grafana Security Advisory and the GitHub Security Advisory GHSA-mpwp-42x6-4wmx.

Workarounds

• Disable the fine-grained access control beta feature by setting the appropriate feature flag in Grafana configuration
• Reduce the number of Organization Admins to minimize the attack surface while the vulnerability remains unpatched
• Implement network segmentation to restrict access to Grafana administrative interfaces
• Consider consolidating to a single organization if multi-organization functionality is not strictly required

# Configuration example - Disable fine-grained access control feature
# Add to grafana.ini or custom.ini configuration file

[feature_toggles]
# Disable the fine-grained access control beta feature
enable = accesscontrol=false