An infinite loop 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_multiple_options() parses CoAP options in a while loop. This loop's exit condition is computed using the previously allocated heap memory required for storing the result of parsing multiple options. If the input heap memory calculation results in zero bytes, the loop exit condition is never met and the loop is not terminated. As a result, the packet parsing function never exits, leading to resource consumption.
Conclusion & alert: CVE-2020-12885 is rated Moderate Risk (53.6/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.23%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.38% | 1.23% | +0.85% |
| 2 | 2025-03-17 | 0.14% | 0.38% | +0.24% |
| 3 | 2023-03-07 | — | 0.14% | — |
Full EPSS history (7 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 7.8 | 2.0 | HIGH |
|
10.0 | 6.9 | [email protected] |
| URL | Tags |
|---|---|
| https://github.com/ARMmbed/mbed-coap/pull/116 | Third Party Advisory |
| https://github.com/ARMmbed/mbed-os/issues/12929 | Third Party Advisory |