etcd having a negative value for cluster node size results in an index out-of-bound panic during service discovery

Summary

### Vulnerability type Data Validation

### Detail When an etcd instance attempts to perform service discovery, if a cluster size is provided as a negative value, the etcd instance will panic without recovery.

### References Find out more on this vulnerability in the [security audit report](https://github.com/etcd-io/etcd/blob/master/security/SECURITY_AUDIT.pdf)

### For more information If you have any questions or comments about this advisory: * Contact the [etcd security committee](https://github.com/etcd-io/etcd/blob/master/security/security-release-process.md#product-security-committee-psc)