Ceph is an open-source distributed storage platform providing object, block, and file storage. In versions prior to 20.2.4 and 19.2.6, the Monitor subscription handler fails to properly authorize access to the configuration-key store, allowing any CephX user with only `mon allow r` capabilities to read the entire store by sending a single crafted MMonSubscribe message. The config-key store holds sensitive secrets including OSD LUKS disk-encryption passphrases and, on cephadm-managed clusters, the SSH private key that cephadm uses to reach every host in the cluster. Because that key grants root on every node under the default cephadm configuration, a low-privileged read-only account can escalate to full cluster and host compromise. This issue is fixed in versions 20.2.4 and 19.2.6
https://github.com/ceph/ceph/security/advisories/GHSA-rg9p-5xcp-wm8h
https://github.com/ceph/ceph/commit/f2840d2fd338ab5de2865f0f78684bbf7b888c84
https://github.com/ceph/ceph/commit/d971bb2b6199f70b1708a20a63fa944ee7a94727