GHSA-XHW7-J96H-C3G5 YAFNET: Pre-Handler Authorization Bypass on Admin Pages Enables Blind SQL Execution via `/Admin/RunSql`

Issue Details: YAFNET's only admin authorization gate is PageSecurityCheckAttribute, implemented as a ResultFilterAttribute that runs after the page handler completes rather than before it. No other gate exists. Any admin OnPost… handler therefore executes its side effects before the filter...