CVE-2020-12887

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

1.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-06-18 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 02:52 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.7% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-06-18 19:15 UTC

Last modified

2026-06-17 02:52 UTC

Exploit probability

1.7% · EPSS, next 30 days

Weakness

CWE-190 · Integer overflow

Record status

Modified

Affected

• Arm mbed-coap 5.1.5

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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