* proper range checking for TryStrToDWord, should resolve all issues in #39406

rtl/objpas/sysutils/sysstr.inc

@@ -1007,10 +1007,14 @@ begin
 end;
 
 function TryStrToDWord(const s: string; Out D: DWord): boolean;
-var Error : word;
+var 
+  Error : word;
+  lq : QWord;
 begin
-  Val(s, D, Error);
-  TryStrToDWord:=Error=0
+  Val(s, lq, Error);
+  TryStrToDWord:=(Error=0) and (lq<=High(DWord));
+  if TryStrToDWord then
+    D:=lq;
 end;
 
 function StrToUInt(const s: string): Cardinal;

tests/webtbs/tw39406.pp

@@ -0,0 +1,14 @@
+{$mode objfpc}
+program fpbug;
+
+uses
+  SysUtils;
+
+var
+  Value:   Cardinal;
+  Success: Boolean;
+begin
+  Success := TryStrToDword('7795000000', Value);
+  if Success then
+    halt(1);
+end.