Heap-based buffer overflow in PolarSSL 1.x before 1.2.17 and ARM mbed TLS (formerly PolarSSL) 1.3.x before 1.3.14 and 2.x before 2.1.2 allows remote SSL servers to cause a denial of service (client crash) and possibly execute arbitrary code via a long hostname to the server name indication (SNI) extension, which is not properly handled when creating a ClientHello message.  NOTE: this identifier has been SPLIT per ADT3 due to different affected version ranges. See CVE-2015-8036 for the session ticket issue that was introduced in 1.3.0.