CVE-2026-28383: Grafana Plugin DoS Vulnerability

CVE-2026-28383 Overview

CVE-2026-28383 is a denial-of-service vulnerability in the Grafana plugin resources endpoint. The endpoint reads the entire HTTP request body into memory without enforcing a size limit. An authenticated user can send a large request body to trigger an out-of-memory condition on the Grafana server. The resulting resource exhaustion can crash the service and interrupt availability for all users.

The issue affects the request handling path for plugin resource calls and requires only low-privilege authenticated access over the network. No user interaction is needed, and the attack does not impact confidentiality or integrity of stored data.

Critical Impact

Authenticated attackers can exhaust server memory and cause a denial of service against Grafana instances by submitting oversized request bodies to the plugin resources endpoint.

Affected Products

• Grafana (plugin resources endpoint) — refer to the vendor advisory for fixed version ranges
• Grafana Enterprise builds derived from affected upstream versions
• Self-hosted and on-premise Grafana deployments exposing plugin endpoints to authenticated users

Discovery Timeline

• 2026-05-13 - CVE-2026-28383 published to NVD
• 2026-05-13 - Last updated in NVD database

Technical Details for CVE-2026-28383

Vulnerability Analysis

The vulnerability is a resource exhaustion flaw in Grafana's plugin resources endpoint. When the endpoint receives an HTTP request, the handler reads the full request body into memory before processing it. Because no maximum body size is enforced, an authenticated client can submit an arbitrarily large payload. The Go runtime allocates memory to back the buffer, and the process can reach an out-of-memory state.

When the Grafana process exhausts available memory, the operating system terminates it or the runtime panics. Dashboards, alerting, and data source proxying all stop functioning. Recovery requires restarting the service and may involve clearing pending sessions.

The issue falls under the broader category of uncontrolled resource consumption ([CWE-770]). Similar patterns appear in web services that call functions equivalent to io.ReadAll on untrusted input without first bounding the reader.

Root Cause

The root cause is the absence of an input size limit on the plugin resources request handler. The handler buffers the entire body before dispatching it to the plugin backend. Without a wrapper such as http.MaxBytesReader or a streaming consumer, a single request can allocate gigabytes of heap memory.

Attack Vector

An attacker needs valid Grafana credentials at any authenticated role level. The attacker sends an HTTP request to the plugin resources endpoint with an oversized body, optionally using chunked transfer encoding to defer the size from headers. Repeating the request, or sending several in parallel, accelerates memory exhaustion and forces the process to terminate.

The vulnerability is described in prose only; no public proof-of-concept exploit code is referenced in the advisory. See the Grafana Security Advisory CVE-2026-28383 for vendor-provided technical detail.

Detection Methods for CVE-2026-28383

Indicators of Compromise

• HTTP requests to plugin resource paths under /api/plugins/ with abnormally large Content-Length values or chunked bodies
• Grafana process restarts, OOM-killer entries in dmesg, or container exit codes indicating memory exhaustion
• Sudden spikes in resident set size (RSS) for the grafana-server process correlated with authenticated API traffic

Detection Strategies

• Inspect web server and reverse proxy logs for requests to plugin resource endpoints with payloads exceeding expected sizes for legitimate plugin traffic
• Correlate authenticated session identifiers with high request body sizes to identify the source account abusing the endpoint
• Alert when Grafana memory usage crosses a configured threshold within a short window, indicating possible exploitation

Monitoring Recommendations

• Export Grafana process metrics (memory, goroutines, request latency) to a monitoring backend and alert on rapid growth
• Capture access logs at the reverse proxy in front of Grafana to retain request size data even after a process crash
• Track authentication events alongside plugin endpoint usage to detect compromised or misused accounts

How to Mitigate CVE-2026-28383

Immediate Actions Required

• Upgrade Grafana to a fixed version as listed in the Grafana Security Advisory CVE-2026-28383
• Restrict network access to Grafana so only trusted users and networks can authenticate
• Rotate or audit Grafana API tokens and user credentials to limit the attacker population that could reach the endpoint

Patch Information

Grafana published a security advisory tracking this issue. Apply the upgrade path documented at the Grafana Security Advisory CVE-2026-28383. The fix introduces a size limit on the plugin resources request body so oversized payloads are rejected before memory allocation.

Workarounds

• Enforce a request body size limit at an upstream reverse proxy such as NGINX or Envoy for requests routed to plugin endpoints
• Set per-process memory limits using cgroups, Kubernetes resource limits, or systemd MemoryMax to contain impact during exploitation
• Disable or restrict plugins that expose resource endpoints if they are not required by the deployment

# NGINX example: cap request body size for Grafana plugin endpoints
location /api/plugins/ {
    client_max_body_size 1m;
    proxy_pass http://grafana_upstream;
}