CVE-2026-21724: Grafana OSS Auth Bypass Vulnerability

CVE-2026-21724 Overview

A vulnerability has been discovered in Grafana OSS where an authorization bypass in the provisioning contact points API allows users with Editor role to modify protected webhook URLs without the required alert.notifications.receivers.protected:write permission. This authorization bypass vulnerability enables users with insufficient privileges to alter sensitive notification configuration settings, potentially allowing attackers to redirect alert notifications to attacker-controlled endpoints or disrupt an organization's incident response workflows.

Critical Impact

Users with Editor role can bypass authorization controls to modify protected webhook URLs in Grafana's alerting system, potentially compromising notification integrity and enabling data exfiltration through manipulated alert destinations.

Affected Products

• Grafana OSS (specific versions not disclosed in advisory)

Discovery Timeline

• 2026-03-26 - CVE CVE-2026-21724 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-21724

Vulnerability Analysis

This authorization bypass vulnerability resides in Grafana OSS's provisioning contact points API. The flaw stems from improper access control validation when handling API requests to modify protected webhook URLs. Specifically, the API endpoint fails to properly verify that users possess the required alert.notifications.receivers.protected:write permission before allowing modifications to protected contact point configurations.

Users assigned the Editor role can exploit this vulnerability over the network without requiring any user interaction. The attack requires authenticated access to a Grafana instance with Editor-level privileges, which is a commonly assigned role in many organizations. Once exploited, an attacker can modify webhook URLs used for alert notifications, potentially redirecting sensitive security alerts to malicious endpoints or disrupting the organization's alerting pipeline.

The vulnerability presents both confidentiality and integrity impacts—attackers can intercept alert data by redirecting webhooks and compromise the integrity of the alerting configuration.

Root Cause

The root cause of this vulnerability is improper authorization checking in the provisioning contact points API. The API implementation does not correctly enforce the alert.notifications.receivers.protected:write permission requirement when processing modification requests from users with the Editor role. This represents a broken access control flaw where the permission boundary between protected and unprotected resources is not properly enforced.

Attack Vector

The attack vector is network-based and requires low-privilege authenticated access (Editor role). An attacker with Editor-level access to a Grafana instance can directly call the provisioning contact points API to modify protected webhook URLs. The attack does not require any user interaction and can be performed through standard API calls.

The exploitation flow involves:

1. An attacker obtains or possesses Editor role credentials for a target Grafana instance
2. The attacker identifies protected contact points with webhook configurations
3. Using the provisioning API, the attacker modifies the webhook URL to point to an attacker-controlled server
4. Subsequent alerts are sent to the malicious endpoint, allowing data exfiltration or alert suppression

For detailed technical information, refer to the Grafana Security Advisory CVE-2026-21724.

Detection Methods for CVE-2026-21724

Indicators of Compromise

• Unexpected modifications to webhook URLs in alerting contact points
• API audit logs showing contact point modifications from Editor-role users
• Alert notifications being sent to unfamiliar or suspicious endpoints
• Changes to protected receiver configurations without corresponding change management records

Detection Strategies

• Monitor Grafana audit logs for API calls to the provisioning contact points endpoint from users without the alert.notifications.receivers.protected:write permission
• Implement alerting on any modifications to protected contact point configurations
• Review Grafana access logs for unusual patterns of API activity targeting notification receivers
• Deploy network monitoring to detect outbound connections from Grafana to unexpected webhook destinations

Monitoring Recommendations

• Enable comprehensive audit logging for all Grafana API endpoints, particularly provisioning-related APIs
• Configure SIEM rules to detect contact point modification events from non-administrative users
• Establish baseline webhook URL configurations and alert on any deviations
• Regularly audit user role assignments and ensure Editor roles are granted only when necessary

How to Mitigate CVE-2026-21724

Immediate Actions Required

• Review and validate all current contact point configurations for unauthorized webhook URL modifications
• Audit Grafana user roles and revoke Editor access from users who do not require it
• Monitor API logs for any suspicious contact point modification activity
• Apply the security patch provided by Grafana as soon as it becomes available
• Consider temporarily restricting access to the provisioning contact points API if feasible

Patch Information

Grafana has released a security advisory addressing this vulnerability. Organizations should consult the Grafana Security Advisory CVE-2026-21724 for specific patch versions and upgrade instructions. Apply the vendor-provided security update as the primary remediation.

Workarounds

• Implement network-level access controls to restrict API access to the provisioning endpoints
• Use API gateway or reverse proxy rules to block or audit modifications to contact point configurations
• Review and minimize the number of users with Editor role assignments
• Deploy additional authentication layers such as mutual TLS for API access where possible
• Consider using read-only provisioning configurations managed through infrastructure-as-code rather than the API

# Example: Audit Grafana users with Editor role
# Review current role assignments in your Grafana instance
# and revoke unnecessary Editor privileges

# Check Grafana server logs for contact point modifications
grep -E "contact.*point|provisioning.*receiver" /var/log/grafana/grafana.log