CVE-2021-40831: The AWS IoT Device SDK v2 for Java, Python, C++ and Node.js appends a user supplied Certificate Authority (CA)

Q: How do I fix CVE-2021-40831?

amazon web services aws-c-io: downgrade or apply the listed mitigation; amazon web services internet of things device software development kit v2: upgrade to 1.5.0; amazon web services internet of things device software development kit v2: upgrade to 1.6.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-40831 being exploited?

CVE-2021-40831 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-40831 affect?

CVE-2021-40831 affects amazon web services aws-c-io, amazon web services internet of things device software development kit v2, amazon web services internet of things device software development kit v2. Severity is medium (CVSS 6.3). 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

Q: How urgent is CVE-2021-40831?

Priority 40/100. On your watchlist

This month

MEDIUM 6.3WATCHLISTDOWNGRADEUPGRADEUPGRADE

CVE-2021-40831 is a medium-severity flaw (CVSS 6.3) affecting amazon web services aws-c-io, amazon web services internet of things device software development kit v2, amazon web services internet of things device software development kit v2. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 com

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.3 (Medium)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.6% (top 50%)
CISA exploited list	No
Weakness	CWE-295
Published	2021-11-23
Last modified	2026-06-17

Publisher (CNA): F-Secure · Vendor: amazon

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-11-23 00:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

amazon amazon web services aws-c-io DOWNGRADE

Affected: 0.10.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.10.7

1. Check installed version

apt-cache policy amazon-web-services-aws-c-io || rpm -q amazon-web-services-aws-c-io || amazon-web-services-aws-c-io --version

2. No fixed release: DOWNGRADE to a release before 0.10.7 (Debian / Ubuntu)

apt-cache madison amazon-web-services-aws-c-io sudo apt install amazon-web-services-aws-c-io=<VERSION_BEFORE_0.10.7> sudo apt-mark hold amazon-web-services-aws-c-io

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list amazon-web-services-aws-c-io sudo dnf downgrade amazon-web-services-aws-c-io-<VERSION_BEFORE_0.10.7> sudo dnf versionlock add amazon-web-services-aws-c-io

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

amazon amazon web services internet of things device software development kit v2 UPGRADE

Affected: < 1.5.0

Fixed in: 1.5.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy amazon-web-services-internet-of-things-device-software-development-kit-v2 || rpm -q amazon-web-services-internet-of-things-device-software-development-kit-v2 || amazon-web-services-internet-of-things-device-software-development-kit-v2 --version

2. UPGRADE to 1.5.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade amazon-web-services-internet-of-things-device-software-development-kit-v2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade amazon-web-services-internet-of-things-device-software-development-kit-v2

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

amazon amazon web services internet of things device software development kit v2 UPGRADE

Affected: < 1.6.0

Fixed in: 1.6.0

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls amazon-web-services-internet-of-things-device-software-development-kit-v2

2. UPGRADE to 1.6.0

npm install amazon-web-services-internet-of-things-device-software-development-kit-v2@">=1.6.0"

amazon amazon web services internet of things device software development kit v2 UPGRADE

Affected: < 1.7.0

Fixed in: 1.7.0

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show amazon-web-services-internet-of-things-device-software-development-kit-v2

2. UPGRADE to 1.7.0

pip install --upgrade "amazon-web-services-internet-of-things-device-software-development-kit-v2>=1.7.0"

amazon amazon web services internet of things device software development kit v2 UPGRADE

Affected: < 1.14.0

Fixed in: 1.14.0

Safe to downgrade to: no unaffected older release

1. Check installed version

2. UPGRADE to 1.14.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade amazon-web-services-internet-of-things-device-software-development-kit-v2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade amazon-web-services-internet-of-things-device-software-development-kit-v2

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-40831?

amazon web services aws-c-io: downgrade or apply the listed mitigation; amazon web services internet of things device software development kit v2: upgrade to 1.5.0; amazon web services internet of things device software development kit v2: upgrade to 1.6.0. Exact commands for each OS are on this page.

Is CVE-2021-40831 being exploited?

CVE-2021-40831 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-40831 affect?

CVE-2021-40831 affects amazon web services aws-c-io, amazon web services internet of things device software development kit v2, amazon web services internet of things device software development kit v2. Severity is medium (CVSS 6.3). 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

How urgent is CVE-2021-40831?

Priority 40/100. On your watchlist

Software pages

Node.js vulnerabilities · Python vulnerabilities · Java vulnerabilities · macOS vulnerabilities · AWS vulnerabilities

Related CVEs

CVE-2021-40830 MEDIUM 6.3 DOWNGRADE UPGRADE The AWS IoT Device SDK v2 for Java, Python, C++ and Node.js appends a user supplied Certificate Authority (CA)
CVE-2021-40828 MEDIUM 6.3 UPGRADE UPGRADE Connections initialized by the AWS IoT Device SDK v2 for Java (versions prior to 1.3.3), Python (versions prio

References

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