CVE-2026-33376

A flaw in Grafana's Auth Proxy IPv6 allow-list incorrectly defaults to a broad /32 subnet mask instead of a strict /128. This misconfiguration allows remote attackers to bypass access restrictions, potentially leading to unauthorized access and data manipulation.

A flaw in Grafana's Auth Proxy IPv6 allow-list defaults to an overly broad /32 mask, potentially allowing unauthorized access. This strictly affects Auth Proxy deployments using IPv6 allow-lists; other authentication methods are unaffected. This has been rated moderate since auth proxy authentication is not enabled by default on grafana shipped on RHEL.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, explicitly specify the intended IPv6 address mask—typically /128 for a single host—within the Grafana Auth Proxy allow-list configuration. This overrides the incorrect default /32 mask, ensuring that network access restrictions are applied strictly as intended. For RHEL: Update the whitelist directive under the [auth.proxy] section in /etc/grafana/grafana.ini. For example, if ::1 is the desired address, configure it explicitly as ::1/128. A restart of the Grafana service (systemctl restart grafana-server) is required for the changes to take effect.