GHSA-xg4h-6gfc-h4m8

### 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](https://github.com/lobuhi) on Github) - Anthropic and Adam Korczynski ([@AdamKorcz](https://github.com/AdamKorcz) on Github)