Prometheus: Azure AD remote-write client secret served in plaintext from the /-/config endpoint

Impact

The client_secret in the Azure AD remote-write configuration was typed as a plain string rather than Prometheus's Secret type, so the redaction that normally masks credentials on the /-/config HTTP endpoint never applied to it. Anyone who can reach that endpoint reads the OAuth client secret verbatim. On a GPU fleet the Prometheus that scrapes DCGM exporters and node metrics is usually reachable by far more people and services than the Azure identity behind it is meant to be - dashboards, tenants with a metrics view, sidecars - so the credential leaks well beyond the monitoring boundary and can then be used against the Azure workspace the fleet remote-writes into. Only deployments that use the azuread remote-write OAuth configuration are affected.

Who can reach it

Any user or process that can issue an HTTP request to the Prometheus /-/config endpoint. Prometheus ships with no authentication of its own, so in most deployments this is anyone with network reach to the server.

What to do

Upgrade to Prometheus 3.5.3 or 3.11.3 (or the equivalent Red Hat errata build), restart the Prometheus process, and then rotate the Azure AD client secret - patching stops future disclosure but does not undo an already-leaked credential. Restart is a single daemon bounce; scrape gaps are the only cost.

References