The security, privacy, and trust are the critical concerns in Vehicular Ad Hoc Networks (VANETs). The Security Credential Management System (SCMS) is one of the most promising PKI-based solutions, which adopts linkage-based pseudonym certificates and has been standardized by IEEE. This paper aims to address the issues of certificate revocation in the SCMS architecture. We propose ESCORT, achieving: (i) a privacy-preserving revocation transparency for linkage-based pseudonym certificates, enhancing the reliability of the SCMS architecture; (ii) an efficient certificate status check for vehicles, eliminating complicated computations in checking CRLs. We analyze the security and feasibility of ESCORT, and experimental results indicate its superior efficiency.