In Contiki 4.5, TCP ISNs are improperly random.

An issue was discovered in Contiki through 3.0 and Contiki-NG through 4.5. The code for parsing Type A domain name answers in ip64-dns64.c doesn't verify whether the address in the answer's length is sane. Therefore, when copying an address of an arbitrary length, a buffer overflow can occur. This bug can be exploited whenever NAT64 is enabled.

Buffer overflows were discovered in Contiki-NG 4.4 through 4.5, in the SNMP agent. Functions parsing the OIDs in SNMP requests lack sufficient allocated target-buffer capacity verification when writing parsed OID values. The function snmpoiddecodeoid() may overwrite memory areas beyond the provided target buffer, when called from snmpmessagedecode() upon an SNMP request reception. Because the content of the write operations is externally provided in the SNMP requests, it enables a remote overwrite of an IoT device's memory regions beyond the allocated buffer. This overflow may allow remote overwrite of stack and statically allocated variables memory regions by sending a crafted SNMP request.

Memory access out of buffer boundaries issues was discovered in Contiki-NG 4.4 through 4.5, in the SNMP BER encoder/decoder. The length of provided input/output buffers is insufficiently verified during the encoding and decoding of data. This may lead to out-of-bounds buffer read or write access in BER decoding and encoding functions.

Buffer overflows were discovered in Contiki-NG 4.4 through 4.5, in the SNMP agent. The function parsing the received SNMP request does not verify the input message's requested variables against the capacity of the internal SNMP engine buffer. If the number of variables in the request exceeds the allocated buffer, a memory write out of the buffer boundaries occurs. This write operation provides a possibility to overwrite other variables allocated in the .bss section by the application. Because the sender of the frame is in control of the content that will be written beyond the buffer limits, and there is no strict process memory separation, this issue may allow overwriting of sensitive memory areas of an IoT device.

Buffer overflows were discovered in Contiki-NG 4.4 through 4.5, in the SNMP bulk get request response encoding function. The function parsing the received SNMP request does not verify the input message's requested variables against the capacity of the internal SNMP engine buffer. When a bulk get request response is assembled, a stack buffer dedicated for OIDs (with a limited capacity) is allocated in snmpenginegetbulk(). When snmpenginegetbulk() is populating the stack buffer, an overflow condition may occur due to lack of input length validation. This makes it possible to overwrite stack regions beyond the allocated buffer, including the return address from the function. As a result, the code execution path may be redirected to an address provided in the SNMP bulk get payload. If the target architecture uses common addressing space for program and data memory, it may also be possible to supply code in the SNMP request payload, and redirect the execution path to the remotely injected code, by modifying the function's return address.