GHSA-xg4h-6gfc-h4m8 etcd: Watch API authorization bypass via open-ended range requests

• Go go.etcd.io/etcd/v3: >= 3.7.0-alpha.0, < 3.7.1 → fixed in 3.7.1 • Go go.etcd.io/etcd/v3: >= 3.6.0, < 3.6.14 → fixed in 3.6.14 • Go go.etcd.io/etcd/v3: < 3.5.33 → fixed in 3.5.33

Impact _What kind of vulnerability is it? Who is impacted?_ A user granted READ permission on a single, exact key can use the Watch gRPC API with `clientv3.WithFromKey()` (an open-ended, "from this key to the end of the keyspace" watch) to receive watch events for every key lexicographically greater than or equal to their permitted key — not just the one key they were granted. This is an authorization bypass in etcd's RBAC enforcement for the Watch API; Range/Get and DeleteRange requests are not affected. It only affects clusters with authentication enabled — clusters running without auth already allow unrestricted read access. Patches _Has the problem been patched? What versions should users upgrade to?_ This vulnerability is patched in the following versions: • etcd 3.7.1 • etcd 3.6.14 • etcd 3.5.33 Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ If upgrading is not immediately possible, the following mitigations reduce exposure: • Audit READ grants. Any READ grant — even on one key — can be leveraged via Watch to read everything after it. Review who holds READ permissions and revoke/tighten any you wouldn't trust with full read access. • Restrict network access. Limit which hosts can reach etcd's client (gRPC) port via firewall rules or network policy, reducing who can attempt exploitation. Reporter • Luis Toro (@lobuhi on Github) • Anthropic and Adam Korczynski (@AdamKorcz on Github)