CVE-2026-15583: Grafana MCP Server SSRF Vulnerability

CVE-2026-15583 Overview

CVE-2026-15583 is a confused-deputy flaw in the Grafana MCP Server. An unauthenticated remote attacker can exfiltrate the server's environment-configured Grafana service-account token by supplying a crafted X-Grafana-URL request header. The vulnerability also enables Server-Side Request Forgery (SSRF) against arbitrary internal services, including cloud metadata endpoints such as AWS Instance Metadata Service (IMDS). The flaw is tracked under [CWE-610: Externally Controlled Reference to a Resource in Another Sphere].

Critical Impact
Unauthenticated attackers can steal Grafana service-account tokens and pivot to internal cloud metadata services, enabling downstream compromise of Grafana tenants and cloud infrastructure.

Affected Products

Grafana MCP Server (Model Context Protocol integration for Grafana)
Deployments exposing the MCP Server with a configured Grafana service-account token
Cloud-hosted instances where the MCP Server can reach internal metadata endpoints

Discovery Timeline

2026-07-15 - CVE-2026-15583 published to NVD
2026-07-15 - Last updated in NVD database

Technical Details for CVE-2026-15583

Vulnerability Analysis

The Grafana MCP Server accepts an X-Grafana-URL header from the client and uses it as the upstream target for outbound requests. The server attaches its environment-configured service-account token to these outbound calls without validating that the destination matches the intended Grafana instance. An attacker who controls the header value can redirect the authenticated request to an attacker-controlled endpoint, which then captures the token in the Authorization header.

The same primitive enables SSRF. By pointing X-Grafana-URL at internal-only URLs, an attacker can reach services that are not exposed to the internet, including cloud provider metadata endpoints. On AWS, this exposes IAM role credentials via the IMDS endpoint when IMDSv1 is enabled.

Root Cause

The root cause is a confused-deputy design pattern. The MCP Server treats an untrusted request header as an authoritative destination while continuing to act with its own privileged credentials. There is no allowlist restricting the value of X-Grafana-URL to the configured Grafana instance and no separation between caller-supplied routing data and server-held secrets.

Attack Vector

Exploitation requires only network access to the MCP Server endpoint. The attacker sends an HTTP request containing an X-Grafana-URL header whose value points to a server they control. The MCP Server forwards the request, including the Grafana service-account bearer token, to that destination. The attacker captures the token from the incoming request headers and reuses it against the legitimate Grafana instance. For SSRF, the header is set to an internal URL such as the cloud metadata endpoint, and the response is returned through the MCP Server's normal reply path. See the Grafana Security Advisory CVE-2026-15583 for full technical details.

Detection Methods for CVE-2026-15583

Indicators of Compromise

Inbound HTTP requests to the MCP Server containing an X-Grafana-URL header pointing to an external or non-configured domain
Outbound connections from the MCP Server host to unexpected destinations, particularly IP literals or cloud metadata addresses such as 169.254.169.254
Grafana audit log entries showing service-account token use from unfamiliar source IP addresses or user agents
Unusual DNS lookups from the MCP Server host for attacker-controlled domains

Detection Strategies

Inspect reverse proxy and application logs for the X-Grafana-URL header and alert when the value does not match the configured Grafana base URL
Correlate MCP Server outbound traffic against an allowlist of expected Grafana endpoints
Monitor Grafana service-account activity for source IPs that differ from the MCP Server's egress addresses

Monitoring Recommendations

Enable egress logging on the MCP Server host and forward events to a centralized data lake for retention and analytics
Alert on any process on the MCP Server host that initiates connections to link-local metadata ranges
Rotate and monitor the Grafana service-account token for anomalous usage patterns following the patch

How to Mitigate CVE-2026-15583

Immediate Actions Required

Upgrade the Grafana MCP Server to the patched release identified in the Grafana Security Advisory CVE-2026-15583
Rotate the Grafana service-account token configured in the MCP Server environment, as it must be assumed compromised
Restrict inbound network access to the MCP Server to trusted clients only
Enforce IMDSv2 on AWS-hosted MCP Server instances to blunt SSRF against instance metadata

Patch Information

Refer to the Grafana Security Advisory CVE-2026-15583 for the fixed version. The patch enforces validation of the destination URL so that the MCP Server only issues authenticated requests to the configured Grafana instance.

Workarounds

Deploy the MCP Server behind a reverse proxy that strips or rejects client-supplied X-Grafana-URL headers
Use egress filtering to prevent the MCP Server host from reaching arbitrary internet destinations and internal metadata endpoints
Scope the Grafana service-account token to the minimum permissions required, limiting the blast radius of token theft

bash

# Example NGINX configuration to strip the attacker-controlled header
location / {
    proxy_set_header X-Grafana-URL "";
    proxy_pass http://grafana-mcp-server:8000;
}