CVE-2026-9703: Viewer role can create, modify and delete Loki alerting rules
Grafana's data source proxy did not apply role-based access control to write requests forwarded to Loki data sources. A user holding only the Viewer role on an affected Grafana instance could send POST, PUT and DELETE requests through the proxy to the Loki rules API (/loki/api/v1/rules), allowing them to create, modify and delete Loki alerting rules. Because those rules are stored by Loki rather than by Grafana, the change took effect for every user of that Loki data source, not only for the Viewer who made the request.
Exploitation requires an authenticated Viewer account on the Grafana instance and a configured Loki data source; no other privileges are needed. Both Grafana OSS and Grafana Enterprise are affected. The defect is in Grafana's data source proxy; Loki itself is not vulnerable and does not need to be patched.
Affected Software
Event History
Frequently Asked Questions
Who is exposed to this issue?
Grafana OSS and Grafana Enterprise instances are affected when they have a Loki data source configured. Any authenticated user assigned only the Viewer role can exploit the issue.
What does an attacker need to do to exploit it?
The attacker needs valid Viewer-level credentials for the affected Grafana instance and access to its data source proxy. They can then send POST, PUT, or DELETE requests to the Loki rules API path through the proxy; no additional privileges or user interaction are required.
What is the impact of a successful exploit?
An attacker can create, alter, or delete Loki alerting rules. Since Loki stores these rules, the changes apply to every user of the affected Loki data source rather than only to the attacking Viewer account.
Does Loki need to be patched?
No. The authorization defect is in Grafana's data source proxy, not in Loki itself.