CVE-2026-33382: Grafana API Request Size Validation Denial of Service

Technical summary

This vulnerability stems from missing or inadequate request body size limits (CWE-400: Uncontrolled Resource Consumption) in multiple Grafana API endpoints. The affected endpoints fail to implement checks that would reject oversized requests before processing begins. When an attacker sends a specially crafted payload with a very large body, the Grafana process attempts to allocate memory to handle it, leading to memory exhaustion. The lack of authentication requirements on some endpoints means this can be triggered by any network-accessible attacker without credentials.

Business impact

Organizations running Grafana face availability risk. An attacker can remotely cause Grafana instances to become unresponsive or crash entirely, disrupting monitoring and observability operations. Since Grafana is often critical infrastructure for system health visibility, outages can cascade into broader operational blindness. Recovery requires manual intervention to restart affected instances. In multi-tenant or shared Grafana deployments, a single attacker can impact all users and monitoring data visibility.

Affected systems

The vulnerability affects Grafana application instances. Specific affected versions have not been disclosed in the provided data; verify the Grafana security advisory and your installed version against vendor guidance to determine exact scope. All deployment models (on-premises, cloud-hosted, containerized) are potentially affected if running a vulnerable version.

Exploitability

The vulnerability has a CVSS score of 7.5 (HIGH severity) with a vector indicating network accessibility, low attack complexity, and no authentication requirement. This reflects the ease with which an attacker can exploit it: a simple HTTP POST or PUT request with an oversized body from the public internet is sufficient. No special tools, knowledge of internal systems, or valid credentials are needed. The primary barrier is network connectivity to the Grafana instance.

Remediation

Apply a security patch from Grafana immediately. The vendor has released updates that implement proper request body size validation and authentication enforcement on previously unauthenticated endpoints. Verify the exact patched versions applicable to your deployment and test in a non-production environment before rolling out broadly.

Patch guidance

Consult the Grafana security advisory released alongside this CVE for specific patched version numbers and availability dates. Prioritize patching instances exposed to untrusted networks. For air-gapped or non-internet-facing Grafana deployments, the risk is lower but should still be addressed in your maintenance cycle. Consider using a reverse proxy or API gateway with request size limits as a temporary mitigation while patches are being tested and deployed.

Detection guidance

Monitor for HTTP requests with unusually large body sizes targeting Grafana API endpoints, particularly unauthenticated endpoints. Log and alert on POST/PUT requests exceeding expected payload sizes (e.g., >50MB depending on your configuration). Track Grafana process memory usage for sudden spikes that could indicate an ongoing attack. In WAF or proxy logs, look for repeated large requests from the same source IP to API paths. Review Grafana access logs for successful requests to vulnerable endpoints before the patch date.

Why prioritize this

This vulnerability merits rapid patching because it combines network accessibility, no authentication requirement, and high availability impact. Denial-of-service attacks against monitoring infrastructure can have cascading consequences for incident response and operational visibility. The ease of exploitation means opportunistic attackers or automated scanning will likely attempt this once CVE details are published. Organizations with Grafana instances on the internet or in DMZs should treat this as urgent.

Risk score, explained

The CVSS 7.5 score reflects the high practical risk. The vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H indicates: Network-accessible attack surface, low complexity (no unusual conditions required), no privileges or user interaction needed, and high impact on availability. Confidentiality and integrity are not affected, which prevents a critical rating, but the combination of accessibility and DoS impact justifies the HIGH severity label.

Frequently asked questions