Summary

An authenticated organization user who can create or edit alert rules in a folder can query a datasource for which they do not have datasources:query permission. The attacker sets the client-controlled query field queryType to __expr__ while retaining the UID of a real datasource.

The alert-rule authorization path treats the query as a server-side expression and skips datasource permission enforcement, while the evaluator subsequently resolves and executes the query against the real datasource identified by datasourceUid.

## Impact

This bypass can expose data accessible through Grafana's configured datasource credentials to a low-privileged user who is not authorized to query that datasource directly. Confidentiality impact is High.

Integrity impact is Low because some datasource backends and configured credentials may permit state-changing queries. No availability impact has been demonstrated.

## Attack prerequisites

- Authenticated, low-privileged user in the same Grafana organization
- Permission to create or edit alert rules in an accessible folder
- No datasources:query permission for the targeted datasource
- Knowledge or discovery of the targeted datasource UID
- No user interaction required

## Technical details / root cause

1. The attacker submits an alert-rule query with queryType: "__expr__" and the UID of a real datasource.
2. The datasource authorization helper skips permission enforcement when query.QueryType == "__expr__".
3. queryType is client-controlled and is not validated against the referenced datasource.
4. During evaluation, Grafana selects and loads the actual datasource using DatasourceUID, not the spoofed queryType.
5. The query therefore executes using Grafana's datasource credentials despite the caller lacking datasources:query.

The root cause is inconsistent query classification between authorization and execution: authorization trusts queryType, while execution trusts DatasourceUID.

## Affected product / component

- Product: Grafana OSS
- Component: Unified Alerting / ngalert
- Area: Alert-rule datasource authorization and query evaluation
- Confirmed version: Grafana OSS 13.0.1
- Affected version range: not yet assessed

## Severity

- CVSS 3.1: 7.1 High
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
- CWE-863: Incorrect Authorization

Scope is Unchanged because the vulnerable authorization decision and resulting impact remain within Grafana's security authority.

## Source

- Researcher: czarflix
- Intigriti report: GRAFANALABS-F996ATD7
- Report URL: https://app.intigriti.com/company/submissions/GRAFANALABS-F996ATD7

## Related report / duplicate assessment

This is a default-Grafana-OSS reproduction of the root cause previously reported in GRAFANALABS-IAQAFIXI. The earlier submission was archived as Not Applicable because its proof of concept depended on Cloud/Enterprise-specific permission mechanisms, and the researcher was invited to demonstrate the issue under default OSS permissions. This report establishes that missing prerequisite and should be treated as the actionable OSS submission, not dismissed as a duplicate.

VUL-2026-0095 and VUL-2026-0126 concern Enterprise Recorded Queries and have different components, endpoints, and root causes; they are related authorization issues but not duplicates.

## Recommended remediation

- Do not exempt a query from datasource authorization based solely on client-controlled queryType.
- Resolve the referenced datasource server-side before authorization and apply datasources:query whenever the resolved UID represents a real datasource.
- Require expression queries to reference only the canonical server-side expression datasource and reject mismatches such as queryType: "__expr__" paired with a real datasource UID.
- Ensure authorization and evaluation use the same canonical datasource identity and fail closed when fields conflict.
- Add regression coverage for an OSS user with folder-level alert-rule edit permission but without datasource query permission, including mismatched queryType and datasourceUid values.