CVE-2026-21723
Description
A flaw was found in Grafana. A remote attacker with very low privileges, or even anonymous access if enabled, can exploit the alertmanager templates test endpoint by mass-executing templates. This can lead to an Out-Of-Memory (OOM) error, causing the Grafana service to crash and resulting in a Denial of Service (DoS).
Statement
This Moderate flaw in Grafana allows a remote attacker to trigger a Denial of Service by repeatedly executing alertmanager templates. While requiring low privileges, or anonymous access if enabled, the high attack complexity limits the immediate threat, as it relies on exhausting memory through mass template execution.
Mitigation
If not required, disable anonymous access to prevent unauthenticated exploitation of the Alertmanager templates test endpoint. Refer to Grafana’s official documentation for configuration details.
To protect against low-privileged authenticated users triggering this flaw, configure a reverse proxy or WAF to block or strictly rate-limit traffic to /api/alertmanager/grafana/config/api/v1/templates/test.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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