Vulnerability · Published Nov 2, 2026 · Assigned by GRAFANA
CVE-2026-81938Arbitrary file read via Alertmanager receiver configuration in Grafana Mimir
High 7.7
In plain English
A high-severity path traversal in Enterprise Metrics (GEM) from Grafana. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).
Official description
Grafana Mimir's Alertmanager rejects tenant-supplied receiver configurations that reference local files, but the check did not cover two HTTP client settings: http_headers.<name>.files and basic_auth.username_file. A tenant permitted to upload an Alertmanager configuration could point these fields at any file readable by the Alertmanager process. When a notification was sent, Alertmanager read the file and put its contents in a header of the outgoing request. By directing the receiver at a server they control, the tenant could read files from the Alertmanager host, such as credentials and configuration. Exploitation requires permission to write the tenant's Alertmanager configuration. Grafana Enterprise Metrics (GEM), which is built on Mimir, is also affected. The issue is fixed in Mimir 3.1.7 and 3.2.2 and in GEM 2.17.20. GEM 2.11 through 2.16 will not receive a fix; users on those versions should upgrade to 2.17.20 or later.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Grafana | Enterprise Metrics (GEM) | 2.11.0 – through 2.16.22.17.0 – before 2.17.20 |
| Grafana | Grafana Mimir | 3.0.4 – before 3.1.73.2.0 – before 3.2.2 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
References
- https://grafana.com/security/security-advisories/cve-2026-81938 vendor-advisory