GHSA-pqj7-jx24-wj7w

### Impact Users can either intentionally or inadvertently create a shard containing `/` characters from VTAdmin such that from that point on, anyone who tries to create a new shard from VTAdmin will receive an error. Attempting to view the keyspace(s) will also no longer work. Creating a shard using `vtctldclient` does not have the same problem because the CLI validates the input correctly.

### Patches v16.0.2, corresponding to [0.16.2 on pkg.go.dev](https://pkg.go.dev/vitess.io/vitess@v0.16.2)

### Workarounds - Always use `vtctldclient` to create shards, instead of using VTAdmin - Disable creating shards from VTAdmin using RBAC - Delete the topology record for the offending shard using the client for your topology server. For example, if you created a shard called `a/b` in keyspace `commerce`, and you are running etcd, it can be deleted by doing something like ``` % etcdctl --endpoints "http://${ETCD_SERVER}" del /vitess/global/keyspaces/commerce/shards/a/b/Shard ```

### References https://github.com/vitessio/vitess/issues/12842

Found during a security audit sponsored by the [CNCF](https://cncf.io) and facilitated by [OSTIF](https://ostif.org).