CVE-2021-40829

TLS hostname validation issues within AWS IoT Device SDKs on macOS

6.3 MediumFix available

Connections 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.

Attack profile

How easy it is to exploit

Attack vector: Adjacent network
Complexity: High
Privileges needed: High
User interaction: Required

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.39%Down 0.9 points since Nov 23, 2021

What each source reports

CVE List Score used 6.3

TLS hostname validation issues within AWS IoT Device SDKs on macOS

Record: CVE-2021-40829
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-02

EUVDEUVD-2021-0029 6.3

Record: EUVD-2021-0029
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-03

GitHub AdvisoriesGHSA-743r-5g92-5vgf 7.3

Improper certificate management in AWS IoT Device SDK v2

Record: GHSA-743r-5g92-5vgf
CVSS 4.0: 7.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-295
Updated: 2026-11-02

NVD 6.3

Record: CVE-2021-40829
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 5.8 MediumAV:A/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-295
Updated: 2026-11-02

OSV 8.8

Record: CVE-2021-40829
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVGHSA-743r-5g92-5vgf 7.3

Improper certificate management in AWS IoT Device SDK v2

Record: GHSA-743r-5g92-5vgf
CVSS 4.0: 7.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-295
Updated: 2026-11-02

OSVPYSEC-2021-862 No score

Record: PYSEC-2021-862
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk` Maven	before 1.4.2	1.4.2
`aws-iot-device-sdk-v2` npm	before 1.5.3	1.5.3
`awsiotsdk` PyPI	before 1.6.1	1.6.1
`software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk` Maven	before 1.4.2, plus listed versions 0.2.30.2.40.2.50.2.60.2.7 Show 42 moreShow less 0.2.80.3.00.3.10.3.20.3.31.0.01.0.11.0.21.0.31.0.41.0.51.0.61.0.71.0.81.0.91.1.01.1.11.2.01.2.11.2.101.2.111.2.121.2.131.2.141.2.151.2.161.2.171.2.181.2.21.2.31.2.41.2.51.2.61.2.71.2.81.2.91.3.01.3.11.3.21.3.31.4.01.4.1	1.4.2
`awsiotsdk` PyPI	before 1.6.1, plus listed versions 0.2.40.2.90.3.01.0.21.0.3 Show 28 moreShow less 1.0.51.0.61.1.01.2.01.2.11.3.01.3.11.3.21.4.01.5.01.5.11.5.101.5.111.5.121.5.131.5.141.5.151.5.161.5.171.5.181.5.21.5.31.5.41.5.51.5.61.5.71.5.81.6.0	1.6.1

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-40829 is a medium vulnerability (CVSS 6.3) in Amazon Web Services Aws Iot Device Sdk V2 For C++, published November 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. Fixed in software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk 1.4.2.