Out-of-Bounds Read in Eclipse tinydtls Certificate Handshake Leading to Denial of Service

Eclipse tinydtls before commit b3efd41ad111a4920f599f51ffa4f5e9f1e72221 contains an out-of-bounds read vulnerability in the check_server_certificate() function that allows unauthenticated attackers to trigger reads beyond valid buffer boundaries by crafting a Certificate handshake message with a specific fragment_length value. Attackers can exploit missing buffer length validation before uint24 reads, memcmp, and memcpy operations during DTLS epoch 0 on both client and server paths to cause denial of service on memory-constrained devices.

Eclipse tinydtls 0.8.2 for Eclipse IoT allows remote attackers to cause a denial of service (DTLS peer crash) by sending a "Change cipher spec" packet without pre-handshake.

Eclipse TinyDTLS through 0.9-rc1 relies on the rand function in the C library, which makes it easier for remote attackers to compute the master key and then decrypt DTLS traffic.