Vulnerability Name:

CVE-2020-12887 (CCN-183627)

Assigned:2020-05-12
Published:2020-05-12
Updated:2021-07-21
Summary: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.
CVSS v3 Severity:7.5 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
6.5 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
5.3 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
4.6 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Low
CVSS v2 Severity:5.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
5.0 Medium (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
Vulnerability Type:CWE-401
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2020-12887

Source: XF
Type: UNKNOWN
armmbed-cve202012887-dos(183627)

Source: CONFIRM
Type: Third Party Advisory
https://github.com/ARMmbed/mbed-coap/pull/116

Source: MISC
Type: Third Party Advisory
https://github.com/ARMmbed/mbed-os/issues/12930

Source: CCN
Type: Mbed OS GIT Repository
Memory leak in MbedOS CoAP library parser - sn_coap_parser_options_parse() #12957

Source: MISC
Type: Third Party Advisory
https://github.com/ARMmbed/mbed-os/issues/12957

Source: MISC
Type: Patch, Third Party Advisory
https://github.com/mjurczak/mbed-coap/commit/4647a68e364401e81dbd370728127d844f221d93

Vulnerable Configuration:Configuration 1:
  • cpe:/a:arm:mbed-coap:5.1.5:*:*:*:*:*:*:*
  • AND
  • cpe:/o:arm:mbed_os:5.15.3:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    arm mbed-coap 5.1.5
    arm mbed os 5.15.3