The vulnerability stems from insufficient SQL function validation in the SQL Manager component. The commit diff shows:
- LOAD_FILE was explicitly added to the 'unauthorized' SQL functions list, indicating it was previously allowed
- A new while-loop was added to checkedSelect() to recursively inspect 'sub_tree' elements of parsed SQL queries for forbidden functions
- The patch adds specific error handling for function-based violations
This demonstrates the pre-patch version of checkedSelect() in RequestSql.php did not properly analyze nested SQL function calls (like LOAD_FILE()), allowing malicious SELECT queries to execute file read operations through SQL injection. The high confidence comes from direct evidence in the patch adding both the function blocklist entry and validation logic improvements targeting function calls in query structures.