An information disclosure vulnerability exists in curl <v8.1.0whendoingHTTP(S)transfers,libcurlmighterroneouslyusethereadcallback(`CURLOPT_READFUNCTION`)toaskfordatatosend,evenwhenthe`CURLOPT_POSTFIELDS`optionhasbeenset,ifthesamehandlepreviouslywasusedtoissuea`PUT`requestwhichusedthatcallback.Thisflawmaysurprisetheapplicationandcauseittomisbehaveandeithersendoffthewrongdataorusememoryafterfreeorsimilarinthesecondtransfer.Theproblemexistsinthelogicforareusedhandlewhenitis(expectedtobe)changedfromaPUTtoaPOST.