The dtls1_clear_queues function in ssl/d1_lib.c in OpenSSL before 0.9.8za 1.0.0 before 1.0.0m and 1.0.1 before 1.0.1h frees data structures without considering that application data can arrive between a ChangeCipherSpec message and a Finished message which allows remote DTLS peers to cause a denial of service (memory corruption and application crash) or possibly have unspecified other impact via unexpected application data.