# CVE-2020-12887: Memory leaks were discovered in the CoAP library in Arm Mbed OS 5.15.3 when using the Arm mbed-coap library 5.1.5.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-06-18 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

Memory leaks were discovered in the CoAP library in Arm Mbed OS 5.15.3 when using the Arm mbed-coap library 5.1.5. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses the CoAP option number field of all options present in the input packet. Each option number is calculated as a sum of the previous option number and a delta of the current option. The delta and the previous option number are expressed as unsigned 16-bit integers. Due to lack of overflow detection, it is possible to craft a packet that wraps the option number around and results in the same option number being processed again in a single packet. Certain options allocate memory by calling a memory allocation function. In the cases of COAP_OPTION_URI_QUERY, COAP_OPTION_URI_PATH, COAP_OPTION_LOCATION_QUERY, and COAP_OPTION_ETAG, there is no check on whether memory has already been allocated, which in conjunction with the option number integer overflow may lead to multiple assignments of allocated memory to a single pointer. This has been demonstrated to lead to memory leak by buffer orphaning. As a result, the memory is never freed.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ARMmbed/mbed-os/issues/12957
- https://github.com/ARMmbed/mbed-os/issues/12930
- https://github.com/mjurczak/mbed-coap/commit/4647a68e364401e81dbd370728127d844f221d93
- https://github.com/ARMmbed/mbed-coap/pull/116

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