In etcd before versions 3.3.23 and 3.4.10, it is possible to have an entry index greater then the number of entries in the ReadAll method in wal/wal.go. This could cause issues when WAL entries are being read during consensus as an arbitrary etcd consensus participant could go down from a runtime panic when reading the entry.
https://github.com/etcd-io/etcd/security/advisories/GHSA-m332-53r6-2w93