This "islandora_advanced_search" sub module enables AJAX updates for advanced search, facet, and search result blocks. The module doesn't sufficiently check block access when arbitrary block ID's are submitted to its publicly accessible AJAX endpoint. This may allow an unauthenticated attacker to retrieve restricted block content. This vulnerability is mitigated by the fact that an attacker must know or guess a restricted block’s machine ID, and the block must contain sensitive content protected by block access or visibility restrictions. Additionally, the submodule is not known to be used by any modern Islandora configurations.