CVE-2026-28374: Authentication Bypass Vulnerability

CVE-2026-28374 Overview

CVE-2026-28374 is a broken access control vulnerability in Grafana that allows users with the Editor role to delete annotations they should not have permission to access. The flaw breaks the platform's authorization model by separating delete permissions from read permissions on annotation objects. Editors cannot create or read the affected annotations but can still issue successful delete operations against them. This issue affects integrity of dashboard annotations without exposing their contents.

Critical Impact
Authenticated Editor accounts can destroy annotation data across a Grafana instance, including annotations created by other users and restricted by access controls.

Affected Products

Grafana (specific versions listed in vendor advisory)
Grafana Enterprise (specific versions listed in vendor advisory)
Self-hosted and managed Grafana deployments exposing the annotations API

Discovery Timeline

2026-05-13 - CVE-2026-28374 published to NVD
2026-05-13 - Last updated in NVD database

Technical Details for CVE-2026-28374

Vulnerability Analysis

The vulnerability is a broken access control issue affecting Grafana's annotations subsystem. Annotations in Grafana mark time-series events on dashboards and can be scoped to specific dashboards, organizations, or users. The platform enforces role-based access control (RBAC) where Editors have permission to create and modify content within their assigned scopes. The defect allows an Editor to issue a delete request against any annotation identifier, including annotations the Editor cannot create or read.

Exploitation requires authenticated access with the Editor role and network reachability to the Grafana API. The attacker does not need to know annotation contents because the delete operation succeeds on identifier alone. Successful exploitation removes operational and forensic context from dashboards without altering or exposing other data. Refer to the Grafana Security Advisory CVE-2026-28374 for affected versions and fix details.

Root Cause

The permission check on the annotation delete endpoint validates the caller's role but does not verify read or ownership permissions on the target annotation. This decoupling allows the delete operation to bypass the resource-level authorization checks applied to create and read operations.

Attack Vector

An authenticated user holding the Editor role sends an HTTP DELETE request to the Grafana annotations API endpoint with the identifier of a targeted annotation. The server processes the request and removes the annotation without enforcing the standard read-access verification. The vulnerability is exploitable over the network using only valid Editor credentials.

No verified exploit code is publicly available. The vulnerability mechanism is documented in the vendor advisory linked above.

Detection Methods for CVE-2026-28374

Indicators of Compromise

Unexpected DELETE requests against /api/annotations/{id} originating from Editor accounts.
Missing annotations on dashboards where audit logs show recent delete operations by non-owner users.
Spikes in annotation delete API call volume from a single authenticated session.

Detection Strategies

Review Grafana audit logs for annotations.delete actions performed by users who lack read access to the targeted annotation.
Correlate Grafana API access logs with user role assignments to identify Editors deleting annotations outside their scope.
Alert on bulk annotation deletion patterns that exceed normal operational baselines.

Monitoring Recommendations

Enable and forward Grafana audit logging to a centralized log platform for retention and analysis.
Track HTTP DELETE traffic against the Grafana annotations API and baseline expected usage per user.
Implement alerts on annotation delete events that target records created by Admins or restricted users.

How to Mitigate CVE-2026-28374

Immediate Actions Required

Upgrade Grafana to a fixed version as specified in the Grafana Security Advisory CVE-2026-28374.
Audit Editor role assignments and revoke the role from accounts that do not require annotation management.
Review recent annotation delete activity in audit logs to identify any unauthorized removals.

Patch Information

Grafana has published fixed versions in the security advisory. Apply the upgrade across all self-hosted Grafana and Grafana Enterprise instances. Managed Grafana Cloud tenants receive patches from the vendor automatically.

Workarounds

Restrict the Editor role to trusted users until patching is complete.
Place Grafana behind a reverse proxy that denies DELETE methods on the annotations API for non-administrative accounts.
Back up annotation data on a regular schedule so deletions can be recovered.

bash

# Example: restrict DELETE on annotations endpoint via nginx reverse proxy
location /api/annotations/ {
    limit_except GET POST {
        deny all;
    }
    proxy_pass http://grafana_backend;
}