Remote user authentication schemes are use to identify auser in the distributed environment. There are three differentfactors commonly use for authentication purpose named aspassword, smart card and biometric. It is been observedthat authentication protocols designed till date are based onpassword. Normally, password is used as a ?rst authenticationfactor, where as other two factors are included accordingto the level of security requirements. In this paper, analysisof 3-factor based protocols is done on the basis of wrongpassword input and stolen smart card vulnerabilities. Paperalso suggest the improvements to control these vulnerabilities.