Description

AWS SDK for Rust v1 adopted defense in depth enhancement for region parameter value

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 Rust. This enhancement validates that a region used to construct an endpoint URL is a valid host label. The change was released on November 6, 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 safely within the requirements of the shared responsibility model, additional safeguards have been added to support secure customer implementations.

Impacted versions: All versions prior to November 6, 2025 release

Patches

On November 6, 2025, an enhancement [1] was made to the AWS SDK for Rust release, which validates the formatting of a region, providing additional safeguards.

Workarounds

No workarounds are needed, but as always developers should ensure that their application is following security best practices:

Implement proper input validation in your application code

Update to the latest AWS SDK for Rust release on a regular basis

Follow AWS security best practices [2] for SDK configuration

References

Contact AWS Security via the vulnerability reporting page or email [email protected].

Acknowledgement

AWS Security thanks Guy Arazi for bringing these customer security considerations to our attention through the coordinated disclosure process.

[1] https://github.com/smithy-lang/smithy-rs/pull/4383 [2] https://docs.aws.amazon.com/sdk-for-rust/latest/dg/security.html

Mitigation

Aliases

References