The vulnerability stems from uncontrolled resource consumption during .xlsx parsing. While the provided patches don't show core library changes, analysis of XLSX format structure and common vulnerability patterns suggests worksheet parsing functions (parse_ws_xml) and shared string handling (parse_shared_strings) are likely candidates. The read function is included as the entry point but with lower confidence. The actual fix in v0.17.0 likely added memory safeguards in these core parsing routines.