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Amazon Web Services Aws C IoApplication · Amazon

CVE-2021-40831

HIGH · 7.2 CVSS v3.1 Published 2021-11-23
Fix available
A fix is available. Upgrade to 1.5.0 / 1.6.0 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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
The AWS IoT Device SDK v2 for Java, Python, C++ and Node.js appends a user supplied Certificate Authority (CA) to the root CAs instead of overriding it on macOS systems. Additionally, SNI validation is also not enabled when the CA has been “overridden”. TLS handshakes will thus succeed if the peer can be verified either from the user-supplied CA or the system’s default trust-store. Attackers with access to a host’s trust stores or are able to compromise a certificate authority already in the host's trust store (note: the attacker must also be able to spoof DNS in this case) may be able to use this issue to bypass CA pinning. An attacker could then spoof the MQTT broker, and either drop traffic and/or respond with the attacker's data, but they would not be able to forward this data on to the MQTT broker because the attacker would still need the user's private keys to authenticate against the MQTT broker. The 'aws_tls_ctx_options_override_default_trust_store_*' function within the aws-c-io submodule has been updated to address this behavior. This issue affects: Amazon Web Services AWS IoT Device SDK v2 for Java versions prior to 1.5.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Python versions prior to 1.7.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for C++ versions prior to 1.14.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Node.js versions prior to 1.6.0 on macOS. Amazon Web Services AWS-C-IO 0.10.7 on macOS.

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

The AWS IoT Device SDK v2 for Java, Python, C++, and Node.js on macOS appends user-supplied CAs to the system's default trust store instead of overriding it, and also fails to enable SNI validation. This allows TLS handshakes to succeed if verified by EITHER the user-supplied CA or the system's default store, enabling attackers with access to compromised CAs (and DNS spoofing capability) to bypass CA pinning and spoof MQTT brokers.

MitigationUpgrade AWS IoT Device SDK to Java 1.5.0+, Python 1.7.0+, C++ 1.14.0+, Node.js 1.6.0+, or aws-c-io 0.10.7+ which fixes the trust store override behavior in the aws_tls_ctx_options_override_default_trust_store_* function.

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
Amazon Web Services Aws C IoApplication
Affected:= 0.10.7
Amazon Web Services Internet Of Things Device Software Development Kit V2Application
Affected:< 1.5.0< 1.6.0< 1.7.0< 1.14.0

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/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. Confirm macOS environment
    Check if the system is running macOS by running 'uname -s' or 'sw_vers'
    Affected if The system is NOT macOS - this vulnerability only affects macOS environments
  2. Identify installed AWS IoT Device SDK v2 language
    Determine which AWS IoT Device SDK v2 language binding is in use (Java, Python, C++, or Node.js) by reviewing project dependencies or import statements
    Affected if The SDK language cannot be determined - you need to identify which SDK variant is in use
  3. Check Java SDK version
    For Java projects, check the version in pom.xml or build.gradle under aws-iot-device-sdk-v2, or run 'mvn dependency:tree | grep aws-iot-device-sdk-v2'
    Affected if Version is less than 1.5.0
  4. Check Node.js SDK version
    Run 'npm list aws-iot-device-sdk-v2' or check package.json dependencies
    Affected if Version is less than 1.6.0
  5. Check Python SDK version
    Run 'pip show aws-iot-device-sdk-v2' or check requirements.txt
    Affected if Version is less than 1.7.0
  6. Check C++ SDK version
    Check the version in CMakeLists.txt or package manager listing for aws-iot-device-sdk-v2
    Affected if Version is less than 1.14.0

You are affected if you are running on macOS AND using any version of AWS IoT Device SDK v2 for Java <1.5.0, Node.js <1.6.0, Python <1.7.0, C++ <1.14.0, or aws-c-io =0.10.7, AND your application uses custom CA certificates for MQTT broker authentication.

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.

dbcve · scoped
Upgrade available Upgrade to 1.5.0 / 1.6.0 / 1.7.0 or later
Fixed in 1.5.01.6.01.7.0
Interim mitigation

Upgrade AWS IoT Device SDK to Java 1.5.0+, Python 1.7.0+, C++ 1.14.0+, Node.js 1.6.0+, or aws-c-io 0.10.7+ which fixes the trust store override behavior in the aws_tls_ctx_options_override_default_trust_store_* function.

Recommended fix High confidence

Upgrade to: AWS IoT Device SDK v2 Java >= 1.5.0, Python >= 1.7.0, C++ >= 1.14.0, Node.js >= 1.6.0, or aws-c-io >= 0.10.8

  1. 1. Identify which AWS IoT Device SDK v2 language/framework you are using (Java, Python, C++, or Node.js)
  2. 2. Identify the current version of the SDK in use by checking your project's dependencies
  3. 3. Upgrade to the fixed version for your SDK: Java: 1.5.0 or later, Python: 1.7.0 or later, C++: 1.14.0 or later, Node.js: 1.6.0 or later
  4. 4. If using aws-c-io directly, upgrade to version 0.10.8 or later
  5. 5. After upgrading, verify the fix is applied by testing MQTT connections on macOS
  6. 6. Ensure your code uses the aws_tls_ctx_options_override_default_trust_store_* function correctly to override (not append to) the system trust store
Caveat No breaking changes expected; this is a security fix that corrects improper certificate validation behavior on macOS

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Amazon Web Services Aws C Io Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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

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Peer-ranked notes from engineers who’ve handled CVE-2021-40831 in production — separate from our analysis above.

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