Elasticsearch 9.4.0 Basic authentication returns 401 Unauthorized – Kibana

After upgrading from elasticsearch/kibana version 9.3.0 to elasticsearch/kibana 9.4.0 I’m no longer able to login with basic authentication via the Authorization Header.

This returns the error 401 Unauthorized.

{
"service": {
"version": "9.4.0",
"type": "kibana",
"state": "available",
"node": {
"roles": [
"background_tasks",
"ui"
]
},
"id": "X03JLrzKRxGOAfdABgkqoA"
},
"ecs": {
"version": "9.3.0"
},
"@timestamp": "2026-05-13T10:48:39.293+02:00",
"message": "Failed to activate user profile: {"error":{"root_cause":[{"type":"security_exception","reason":"unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}}],"type":"security_exception","reason":"unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}},"status":401}.",
"log": {
"level": "ERROR",
"logger": "plugins.security.user-profile"
},
"process": {
"pid": 121084,
"uptime": 163.995308519
},
"trace": {
"id": "bce5939754255e20e763798648dbe844"
},
"transaction": {
"id": "8fba08a59c0f9838"
}
}

{
"http": {
"response": {
"status_code": 401
},
"request": {
"method": "get",
"path": "/app/{id}/{any*}"
}
},
"error": {
"message": "security_exception\n\tRoot causes:\n\t\tsecurity_exception: unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]"
},
"service": {
"version": "9.4.0",
"type": "kibana",
"state": "available",
"node": {
"roles": [
"background_tasks",
"ui"
]
},
"id": "X03JLrzKRxGOAfdABgkqoA"
},
"ecs": {
"version": "9.3.0"
},
"@timestamp": "2026-05-13T10:48:39.293+02:00",
"message": "401 Unauthorized",
"log": {
"level": "ERROR",
"logger": "http"
},
"process": {
"pid": 121084,
"uptime": 163.995723184
},
"trace": {
"id": "bce5939754255e20e763798648dbe844"
},
"transaction": {
"id": "8fba08a59c0f9838"
}
}