DoS Vulnerability in Templates Test endpoint

Medium
Advisory ID:CVE-2026-21723
Published:2026-07-22
Product:Grafana
CVSS Score:5.3
CVSS Vector:CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Fixed Versions:
>=11.6.11
>=12.0.10
>=12.1.7
>=12.2.5
>=12.3.3

Summary

The alertmanager templates test endpoint (/api/alertmanager/grafana/config/api/v1/templates/test) can execute templates with no memory limits. Mass-executing templates in a short period causes OOM and crashes the Grafana service. The endpoint requires very low privileges and is exploitable with anonymous access enabled.

Thanks to the researcher nacl for this report!