Grafana: Auth Proxy cache key collision authenticates a low-privileged user as an administrator

Impact

On self-managed Grafana using Auth Proxy with identity caching enabled (sync_ttl greater than zero), the cache key concatenates the username and forwarded identity attributes with no delimiter, so two distinct identities can produce one key. A user who shapes their own attributes to collide with a higher-privileged user's, while that user's cache entry is still live, is authenticated as them - up to Administrator. Grafana is where a GPU shop's DCGM, thermal, fabric and job dashboards live, along with data source credentials that frequently reach further into the fleet, and admin there also means control of alerting, which is how operators learn a node is failing. Scope is narrow: only Auth Proxy deployments with caching on, and the collision has to land inside the cache window (AC:H).

Who can reach it

Remote authenticated user behind the same Auth Proxy who controls their own forwarded identity attributes. No Grafana admin rights needed, but the attempt must coincide with a live cache entry for the victim.

What to do

Upgrade to the fixed Grafana release named in the vendor advisory for CVE-2026-14199. Without an upgrade window, set sync_ttl to 0 to disable Auth Proxy identity caching - that closes it immediately, at the cost of an identity lookup on every request. Either path costs a Grafana service restart and touches no GPU nodes. If you suspect exploitation, review Grafana admin actions and rotate any data source credentials stored in the instance.

References

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