An issue was discovered by Elastic whereby sensitive information may be recorded in Kibana logs in the event of an error. Elastic has released Kibana 8.11.1 which resolves this issue. The error message recorded in the log may contain account credentials for the kibana_system user, API Keys, and credentials of Kibana end-users. The issue occurs infrequently, only if an error is returned from an Elasticsearch cluster, in cases where there is user interaction and an unhealthy cluster (for example, when returning circuit breaker or no shard exceptions).
https://discuss.elastic.co/t/8-11-1-7-17-15-security-update-esa-2023-25/347149