CVE-2021-40829
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 · uneditedConnections initialized by the AWS IoT Device SDK v2 for Java (versions prior to 1.4.2), Python (versions prior to 1.6.1), C++ (versions prior to 1.12.7) and Node.js (versions prior to 1.5.3) did not verify server certificate hostname during TLS handshake when overriding Certificate Authorities (CA) in their trust stores on MacOS. This issue has been addressed in aws-c-io submodule versions 0.10.5 onward. This issue affects: Amazon Web Services AWS IoT Device SDK v2 for Java versions prior to 1.4.2 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Python versions prior to 1.6.1 on macOS. Amazon Web Services AWS IoT Device SDK v2 for C++ versions prior to 1.12.7 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Node.js versions prior to 1.5.3 on macOS. Amazon Web Services AWS-C-IO 0.10.4 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 confidenceThe AWS IoT Device SDK v2 for Java, Python, C++, and Node.js failed to verify server certificate hostname during TLS handshake when custom Certificate Authorities were configured in trust stores on macOS. This TLS certificate validation bypass in aws-c-io version 0.10.4 allows man-in-the-middle attacks on affected SDK versions running on macOS.
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< 1.4.2< 1.5.3< 1.6.1< 1.12.7CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/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 checksWork through these to decide whether this CVE applies to you.
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Identify AWS IoT Device SDK v2 installationLocate the SDK in your environment. For Python, run 'pip show aws-iot-device-sdk-v2'. For Node.js, check 'npm list aws-iot-device-sdk-v2'. For Java/C++, check your project dependencies or build configuration.Affected if The SDK is installed and the version falls below 1.4.2 (Java), 1.5.3 (Node.js), 1.6.1 (Python), or 1.12.7 (C++)
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Confirm operating system is macOSRun 'uname -s' or check system information. This vulnerability only affects macOS environments.Affected if The environment is running macOS; the flaw does not apply on other operating systems
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Check for custom Certificate Authority configurationInspect your SDK trust store configuration for custom CA certificates. In code, look for AWS_IO_CA_CERT_PATH, AWS_CONFIG_FILE with custom CA settings, or programmatic trust store configuration.Affected if Custom CAs are configured in the trust store; the vulnerability only triggers when custom CAs are present
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Verify aws-c-io submodule versionCheck the included aws-c-io version. For Python, inspect the installed package files or run 'pip show aws-c-io'. For Node.js, check node_modules/aws-c-io/package.json. For Java/C++, examine your dependency tree.Affected if The aws-c-io version is 0.10.4 specifically, which contains the hostname verification bypass
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Check if TLS hostname verification is disabledReview your SDK client configuration for any TLS settings. Look for verify=True/False settings or AWS_IO_TLS_VERIFY mode configuration in your application code or configuration files.Affected if Hostname verification is explicitly disabled or custom CA configuration is present without proper verification
You are affected if running AWS IoT Device SDK v2 on macOS with a version below the patched releases AND custom Certificate Authorities are configured in your trust store.
Generated from the published advisory. Verify against your own configuration.
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 · scoped1.4.21.5.31.6.1
Upgrade AWS IoT Device SDK v2 to versions Java 1.4.2+, Python 1.6.1+, C++ 1.12.7+, or Node.js 1.5.3+ which include the patched aws-c-io 0.10.5+ submodule with proper hostname verification.
Java: >=1.4.2, Python: >=1.6.1, C++: >=1.12.7, Node.js: >=1.5.3 (or aws-c-io >=0.10.5)
- 1. Identify which AWS IoT Device SDK v2 language binding is in use (Java, Python, C++, or Node.js)
- 2. Check the currently installed version of the SDK
- 3. For Java: upgrade to version 1.4.2 or later
- 4. For Python: upgrade to version 1.6.1 or later
- 5. For C++: upgrade to version 1.12.7 or later
- 6. For Node.js: upgrade to version 1.5.3 or later
- 7. Verify the upgrade was successful by checking the SDK version
- 8. Test that TLS connections with certificate validation work correctly on macOS
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40829 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-40829 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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