CVE-2021-40830: Inconsistent CA override function behavior within AWS IoT Device SDKs on Unix systems

What it is stated by the CNA

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 Unix systems. 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. …

weakness

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 Unix systems. 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.

affected

Amazon Web Services AWS IoT Device SDK v2 for Java; Amazon Web Services AWS IoT Device SDK v2 for Python; Amazon Web Services AWS IoT Device SDK v2 for C++; Amazon Web Services AWS IoT Device SDK v2 for Node.js; Amazon Web Services AWS-C-IO

published ranges

amazon web services aws-c-io 0.10.4; amazon web services internet of things device software development kit v2 < 1.5.0; amazon web services internet of things device software development kit v2 < 1.5.3; amazon web services internet of things device software development kit v2 < 1.6.1; and 1 more on the CVE page

fixed in

1.5.0; 1.6.1; 1.12.7; 1.5.3

fixed by package (from OSV advisories)

software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk (Maven): 1.5.0 GHSA-c4rh-4376-gff4awsiotsdk (PyPI): 1.6.1 GHSA-c4rh-4376-gff4 PYSEC-2021-863aws-iot-device-sdk-v2 (npm): 1.5.3 GHSA-c4rh-4376-gff4

later fixes (from OSV advisories)

awsiotsdk 1.6.1 is inside a range CVE-2021-40831 (GHSA-j3f7-7rmc-6wqj) lists as affected. That advisory is fixed in 1.7.0.aws-iot-device-sdk-v2 1.5.3 is inside a range CVE-2021-40831 (GHSA-j3f7-7rmc-6wqj) lists as affected. That advisory is fixed in 1.6.0.

severity

6.3 CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H

assigned by

F-SecureUS

published

2021-11-22

check us github.com github.com github.com github.com

Exploit code held, dated

exploit code

None held in the PoC-in-GitHub feed. A public repository changes this brief.

What moved held, dated

18 observations held. A step marked with a scoring model moved because the measurement was replaced, not because the vulnerability changed.

Outside the record researched, cited

This section reads the record's references and adds cited findings from outside it. It needs an account. Everything above is held facts and is complete without it.

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How to check this

Every value above is held with two dates: when it was true upstream (as_of) and when we recorded it (tx_from). Re-derive the exploit probability as it stood on any date:

SELECT value, source, source_version, as_of, tx_from
FROM volatile_valid_as_of('CVE-2021-40830', '2026-10-29T23:59:59.999999Z', now());