Buffer over-read vulnerability in the dtls_sha256_update function in Contiki-NG tinyDTLS through master branch 53a0d97 allows remote attackers to cause a denial of service via crafted data packet.

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers allow remote attackers to reuse the same epoch number within two times the TCP maximum segment lifetime, which is prohibited in RFC6347. This vulnerability allows remote attackers to obtain sensitive application (data of connected clients).

An assertion failure discovered in in check_certificate_request() in Contiki-NG tinyDTLS through master branch 53a0d97 allows attackers to cause a denial of service.

Buffer over-read vulnerability in Contiki-NG tinyDTLS through master branch 53a0d97 allows attackers obtain sensitive information via crafted input to dtls_ccm_decrypt_message().

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.

An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a large epoch number. This vulnerability allows remote attackers to cause a denial of service and false-positive packet drops.

An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with different epoch numbers in the packets Client_Hello, Client_key_exchange, and Change_cipher_spec, which may cause denial of service.

In Contiki 4.5, TCP ISNs are improperly random.

Contiki-NG is an operating system for internet-of-things devices. In versions 4.9 and prior, when a packet is received, the Contiki-NG network stack attempts to start the periodic TCP timer if it is a TCP packet with the SYN flag set. But the implementation does not first verify that a full TCP header has been received. Specifically, the implementation attempts to access the flags field from the TCP buffer in the following conditional expression in the `check_for_tcp_syn` function. For this reason, an attacker can inject a truncated TCP packet, which will lead to an out-of-bound read from the packet buffer. As of time of publication, a patched version is not available. As a workaround, one can apply the changes in Contiki-NG pull request #2510 to patch the system.

Contiki-NG is an operating system for internet-of-things devices. In versions 4.9 and prior, when processing the various IPv6 header fields during IPHC header decompression, Contiki-NG confirms the received packet buffer contains enough data as needed for that field. But no similar check is done before decompressing the IPv6 address. Therefore, up to 16 bytes can be read out of bounds on the line with the statement `memcpy(&ipaddr->u8[16 - postcount], iphc_ptr, postcount);`. The value of `postcount` depends on the address compression used in the received packet and can be controlled by the attacker. As a result, an attacker can inject a packet that causes an out-of-bound read. As of time of publication, a patched version is not available. As a workaround, one can apply the changes in Contiki-NG pull request #2509 to patch the system.