CVE-2021-40831
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Missing SNI validation and inconsistent CA override function behavior within AWS IoT Device SDKs on Apple devices
rank 24 = 0 + 18 + 0 + 6 + 0
rank@v1 · backlog
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00636 · without this subject the record ranks 24
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 7.2, from NVD · without this subject the record ranks 6
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 24
How much of the world it touches
NVD CPE configurations
5 products in the CPE ranges · without this subject the record ranks 18
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 24
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-295, improper certificate validation. The index holds 1669 prior instances of this class, 6 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Show full BOD 26-04 deadline
CISA has not scored it, so the directive's own defaults apply: automatable no, technical impact total. Calendar days from the KEV listing or from when you find it on a system, whichever is first. Federal agencies are bound from 7 Dec 2026, and contracts often carry it to suppliers. The directive and its table
Exploit Status & Known PoCs a ladder, not a score
Current rung: Nothing observed in held sources.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
Affected & Fixed Versions as published
Show all 5 published ranges
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
$31,700 = $4.99M incident cost x 1 exposure x 0.00636 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
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 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. receipt
Read the rest of the CNA's description
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.
NVD's analysis a second authority
- severity
- 7.2 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- weakness
- CWE-295
- affected versions
- amazon web services aws-c-io 0.10.7; 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 < 1.6.0; and 2 more, listed in full below
- also scored by
- cve-notifications-us@f-secure.com 6.3 CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
The CNA scored it 6.3 and NVD 7.2. Both are shown because both were published; we do not pick one.
check it yourself github.com github.com github.com github.com github.com receipt
Dated events
Movement the material steps
Show all 19 observations
19 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
The record had been public for 4 years, 9 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-295, improper certificate validation. The index holds 1669 prior instances of this class, 6 KEV-listed. The nearest of its KEV-listed records are drawn beside this. cwe-consequences@4.20
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
1669 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
No record cites this identifier and it carries no alias. Its defect family is below.
Its defect family
amazon web services aws iot device sdk v2 for java
Of the 4 records in this advisory, this is the only one holding a stated fix version: 1.5.0; 1.7.0; 1.14.0; 1.6.0.
Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.
Family membership: held values
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What usually comes next
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