The GitHub commit shows critical modifications to sanitize_sql_hash_for_conditions where a 'top_level' parameter was added and nested hash processing was restricted. The original implementation allowed arbitrary nested hash processing (via recursive calls) which could be exploited to inject SQL fragments. The added 'raise ActiveRecord::StatementInvalid' in non-top-level nested cases and test cases validating this behavior confirm this was the attack vector. The CVE description explicitly references improper handling of nested hashes in ActiveRecord's where method implementation, which maps directly to this function's responsibility for processing query conditions.