CVE-2026-27880: Grafana DOS Vulnerability

CVE-2026-27880 Overview

CVE-2026-27880 is a memory exhaustion vulnerability in Grafana's OpenFeature feature toggle evaluation endpoint. The endpoint fails to implement proper bounds checking when reading input values into memory, allowing remote attackers to send specially crafted requests that cause the application to consume excessive memory resources, ultimately leading to out-of-memory crashes and service denial.

Critical Impact

This vulnerability enables unauthenticated remote attackers to crash Grafana instances through memory exhaustion attacks, disrupting critical monitoring and observability infrastructure.

Affected Products

• Grafana (multiple versions)
• Grafana Enterprise (multiple versions)
• Self-hosted and cloud Grafana deployments utilizing OpenFeature feature toggles

Discovery Timeline

• 2026-03-27 - CVE-2026-27880 published to NVD
• 2026-03-31 - Last updated in NVD database

Technical Details for CVE-2026-27880

Vulnerability Analysis

This vulnerability is classified under CWE-787 (Out-of-bounds Write), though its primary impact manifests as a denial-of-service condition through memory exhaustion. The OpenFeature feature toggle evaluation endpoint in Grafana accepts user-supplied data without implementing proper size limits or bounds checking. When processing evaluation requests, the endpoint reads values directly into memory without validating the size of incoming data payloads.

The vulnerability can be exploited remotely over the network without requiring authentication or user interaction. Successful exploitation results in complete availability impact, causing the Grafana service to crash due to memory exhaustion. While confidentiality and integrity are not directly affected, the denial-of-service condition can significantly impact organizations relying on Grafana for monitoring and alerting capabilities.

Root Cause

The root cause of this vulnerability lies in the improper handling of unbounded input data in the OpenFeature feature toggle evaluation endpoint. The code responsible for processing feature toggle evaluations allocates memory based on user-controlled input without implementing proper size validation or memory allocation limits. This allows attackers to provide arbitrarily large values that get read into memory, eventually exhausting available system resources.

Attack Vector

An attacker can exploit this vulnerability by sending HTTP requests to the OpenFeature feature toggle evaluation endpoint with excessively large payload values. The attack requires network access to the Grafana instance but does not require any authentication credentials or special privileges. By repeatedly sending requests with large payloads or a single request with an extremely large value, the attacker can force the Grafana process to allocate memory until the system runs out of available memory, triggering an out-of-memory condition that crashes the service.

The attack can be performed remotely with low complexity, making it particularly dangerous for internet-exposed Grafana instances. Organizations using Grafana for critical infrastructure monitoring may experience significant operational impact if their monitoring dashboards and alerting systems become unavailable.

Detection Methods for CVE-2026-27880

Indicators of Compromise

• Unusual memory consumption patterns on Grafana server processes
• Unexpected out-of-memory (OOM) killer activity on systems hosting Grafana
• Abnormally large HTTP request payloads targeting the feature toggle evaluation endpoint
• Grafana service crashes or restarts without apparent cause
• Log entries indicating memory allocation failures or resource exhaustion

Detection Strategies

• Monitor Grafana process memory usage and alert on abnormal growth patterns
• Implement web application firewall (WAF) rules to detect and block oversized requests to feature toggle endpoints
• Configure application-level logging to capture request sizes to the OpenFeature evaluation endpoint
• Deploy network intrusion detection signatures for anomalous request patterns targeting Grafana

Monitoring Recommendations

• Set up alerting thresholds for Grafana process memory utilization exceeding normal operational baselines
• Monitor HTTP request body sizes at the load balancer or reverse proxy level
• Track Grafana service restart frequency and correlate with potential attack windows
• Implement centralized logging to detect patterns of exploitation attempts across multiple Grafana instances

How to Mitigate CVE-2026-27880

Immediate Actions Required

• Review the Grafana Security Advisory CVE-2026-27880 for specific patched versions and upgrade guidance
• Apply vendor-provided security patches as soon as they become available
• Implement request size limits at the reverse proxy or load balancer level to prevent oversized payloads
• Consider temporarily restricting access to the OpenFeature feature toggle endpoint if not required for operations
• Monitor Grafana instances for signs of exploitation while patches are being deployed

Patch Information

Grafana has released security updates to address this vulnerability. Organizations should consult the official Grafana Security Advisory for specific version information and upgrade instructions. The patches implement proper bounds checking and input validation for the OpenFeature feature toggle evaluation endpoint to prevent memory exhaustion attacks.

Workarounds

• Configure reverse proxy or web server request body size limits to restrict maximum payload sizes
• Implement network-level access controls to limit exposure of Grafana instances to trusted networks only
• Deploy rate limiting on the feature toggle evaluation endpoint to reduce the impact of repeated exploitation attempts
• If OpenFeature feature toggles are not in use, consider disabling or restricting access to the evaluation endpoint
• Use container memory limits or cgroups to prevent a single Grafana instance from exhausting all system memory

# Example nginx configuration to limit request body size
# Add to your nginx server block or location for Grafana
client_max_body_size 1m;

# Rate limiting configuration
limit_req_zone $binary_remote_addr zone=grafana_limit:10m rate=10r/s;

location /api/featuretoggle {
    limit_req zone=grafana_limit burst=20 nodelay;
    proxy_pass http://grafana_backend;
}