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MbedOperating system

CVE-2019-17212

CRITICAL · 9.8 CVSS v3.1 Published 2019-11-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Buffer overflows were discovered in the CoAP library in Arm Mbed OS 5.14.0. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses CoAP input linearly using a while loop. Once an option is parsed in a loop, the current point (*packet_data_pptr) is increased correspondingly. The pointer is restricted by the size of the received buffer, as well as by the 0xFF delimiter byte. Inside each while loop, the check of the value of *packet_data_pptr is not strictly enforced. More specifically, inside a loop, *packet_data_pptr could be increased and then dereferenced without checking. Moreover, there are many other functions in the format of sn_coap_parser_****() that do not check whether the pointer is within the bounds of the allocated buffer. All of these lead to heap-based or stack-based buffer overflows, depending on how the CoAP packet buffer is allocated.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A buffer overflow vulnerability exists in the CoAP library of Arm Mbed OS 5.14.0. The function sn_coap_parser_options_parse() and related sn_coap_parser_****() functions fail to properly validate that the packet data pointer remains within buffer bounds during parsing. Specifically, the pointer can be incremented and dereferenced without checking if it exceeds the allocated buffer size, leading to heap-based or stack-based buffer overflows depending on how the CoAP packet buffer is allocated.

MitigationImplement strict bounds checking in all CoAP parser functions to verify the pointer remains within the received packet buffer before dereferencing. Input validation should confirm buffer size is sufficient before parsing options. Consider adding fuzz testing for the CoAP parser.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MbedOperating system
Affected:= 5.13.2= 5.14.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Mbed OS version
    Check the mbed-os/version.h file or the version reported by the build system. This is typically found in the mbed-os directory under include/version.h or can be queried via 'mbed --version' if the CLI is installed. Alternatively, check the firmware manifest or build configuration that specifies the mbed-os library version.
    Affected if The installed Mbed OS version is 5.13.2 or 5.14.0 exactly.
  2. Confirm CoAP library is in use
    Review the project configuration (mbed-app.json or CMakeLists.txt) to determine if the CoAP library (sn_coap) is included as a dependency. Look for 'sn_coap' in the libraries section or the module configuration.
    Affected if The project links against or includes the CoAP library module.
  3. Verify CoAP packet processing is enabled
    Examine the application source code to confirm that CoAP packet parsing functions are being called at runtime. Search for usage of functions such as sn_coap_parser_options_parse(), sn_coap_parser(), or initialization of CoAP handlers that process incoming packets.
    Affected if The application code calls CoAP parser functions to process network packets.
  4. Assess network exposure
    Determine whether the device processes CoAP packets from untrusted or external network sources. Check if the CoAP endpoint is accessible over the network and accepts packets from non-local sources.
    Affected if The device accepts and parses CoAP packets from network sources outside the trusted local environment.

A user is affected if they are running Mbed OS version 5.13.2 or 5.14.0 with the CoAP library enabled and processing external CoAP packets, as this triggers the vulnerable parsing code path.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement strict bounds checking in all CoAP parser functions to verify the pointer remains within the received packet buffer before dereferencing. Input validation should confirm buffer size is sufficient before parsing options. Consider adding fuzz testing for the CoAP parser.

Fix this in Mbed Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-17212 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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