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3.7
AWS SDK for JavaScript v3 Improper Region Handling
published 10 months ago
Summary
A security enhancement has been made to the AWS SDK for JavaScript v3 to validate region input to prevent misdirecting API calls to non-existent or non-AWS hosts. This matters because it protects against accidental misconfiguration that could compromise API call routing. To stay secure, ensure your application follows security best practices, such as proper input validation, and keep your software up to date with the latest patches.
What to do
- Update smithy config-resolver to version 4.4.0.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| npm | smithy | config-resolver |
< 4.4.0 Fix: upgrade to 4.4.0
|
Original advisory text
AWS SDK for JavaScript v3 adopted defense in depth enhancement for region parameter value
CVSSv3.1 Rating: 3.7 (LOW)
Summary
This notification is related to the use of specific values for the region input field when calling AWS services. An actor with access to the environment in which the SDK is used could set the region input field to an invalid value.
A defense-in-depth enhancement has been implemented in the AWS SDK for JavaScript v3 (versions 3.723.0 and later). This enhancement validates that a region used to construct an endpoint URL is a valid host label. The change was released on November 15, 2025. This advisory is informational to help customers understand their responsibilities regarding configuration security.
Impact
Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. While the SDK was functioning as designed, additional safeguards have been added to support secure customer implementations.
Impacted versions: @smithy/config-resolver <4.4.0
Patches
On November 15, 2025, an enhancement was made to the AWS SDK for JavaScript v3 (versions 3.723.0 and later) release, which validates the formatting of a region, providing additional safeguards. A feature enhancement was implemented in @smithy/config-resolver v4.4.0. This enhancement provides additional configuration validation safeguards but does not address a security vulnerability.
Workarounds
No workarounds are needed, but as always you should ensure that your application is following security best practices:
- Implement proper input validation in your application code
- Update to the latest AWS SDK for Javascript v3 release on a regular basis
- Follow AWS security best practices [1] for SDK configuration
Resources
Contact AWS Security via the vulnerability reporting page or email [[email protected]](mailto:[email protected]).
Acknowledgement
AWS Security thanks Guy Arazi for bringing these customer security considerations to our attention through the coordinated disclosure process.
[1] https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/security.html
Summary
This notification is related to the use of specific values for the region input field when calling AWS services. An actor with access to the environment in which the SDK is used could set the region input field to an invalid value.
A defense-in-depth enhancement has been implemented in the AWS SDK for JavaScript v3 (versions 3.723.0 and later). This enhancement validates that a region used to construct an endpoint URL is a valid host label. The change was released on November 15, 2025. This advisory is informational to help customers understand their responsibilities regarding configuration security.
Impact
Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. While the SDK was functioning as designed, additional safeguards have been added to support secure customer implementations.
Impacted versions: @smithy/config-resolver <4.4.0
Patches
On November 15, 2025, an enhancement was made to the AWS SDK for JavaScript v3 (versions 3.723.0 and later) release, which validates the formatting of a region, providing additional safeguards. A feature enhancement was implemented in @smithy/config-resolver v4.4.0. This enhancement provides additional configuration validation safeguards but does not address a security vulnerability.
Workarounds
No workarounds are needed, but as always you should ensure that your application is following security best practices:
- Implement proper input validation in your application code
- Update to the latest AWS SDK for Javascript v3 release on a regular basis
- Follow AWS security best practices [1] for SDK configuration
Resources
Contact AWS Security via the vulnerability reporting page or email [[email protected]](mailto:[email protected]).
Acknowledgement
AWS Security thanks Guy Arazi for bringing these customer security considerations to our attention through the coordinated disclosure process.
[1] https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/security.html
Internet-facing
14 days
Internal
60 days
- Not known to be exploited
- Can be exploited automatically (estimated)
- Gives an attacker partial control (estimated)
Type
CWE-20Improper Input Validation
Timeline
Published8 Jan 2026
Updated13 Mar 2026
First seen6 Mar 2026
Sources
GHSA-6475-r3vj-m8vf · GHSA
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