CVE-2022-23536: Cortex's Alertmanager can expose local files content via specially crafted config

Cortex provides multi-tenant, long term storage for Prometheus. A local file inclusion vulnerability exists in Cortex versions 1.13.0, 1.13.1 and 1.14.0, where a malicious actor could remotely read local files as a result of parsing maliciously crafted Alertmanager configurations when submitted to the Alertmanager Set Configuration API. Only users of the Alertmanager service where -experimental.alertmanager.enable-api or enable_api: true is configured are affected. Affected Cortex users are advised to upgrade to patched versions 1.13.2 or 1.14.1. However as a workaround, Cortex administrators may reject Alertmanager configurations containing the api_key_file setting in the opsgenie_configs section before sending to the Set Alertmanager Configuration API.