Vulnerability · Published Jun 18, 2020 · Assigned by mitre
CVE-2020-12883
Critical 9.1
In plain English
A critical-severity security flaw in the affected software. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.8% (higher than 78% of all known vulnerabilities).
Official description
Buffer over-reads were discovered in the CoAP library in Arm Mbed OS 5.15.3. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses CoAP input linearly using a while loop. Once an option is parsed in a loop, the current point (*packet_data_pptr) is increased correspondingly. The pointer is restricted by the size of the received buffer, as well as by the option delta and option length bytes. The actual input packet length is not verified against the number of bytes read when processing the option extended delta and the option extended length. Moreover, the calculation of the message_left variable, in the case of non-extended option deltas, is incorrect and indicates more data left for processing than provided in the function input. All of these lead to heap-based or stack-based memory location read access that is outside of the intended boundary of the buffer. Depending on the platform-specific memory management mechanisms, it can lead to processing of unintended inputs or system memory access violation errors.
Affected products (as reported)
References
- https://github.com/ARMmbed/mbed-os/issues/12925 x_refsource_MISC
- https://github.com/ARMmbed/mbed-os/issues/12926 x_refsource_MISC
- https://github.com/ARMmbed/mbed-os/issues/12927 x_refsource_MISC
- https://github.com/ARMmbed/mbed-coap/pull/116 x_refsource_CONFIRM