GHSA-6475-r3vj-m8vf

What it actually does

This issue is an improper input validation weakness in the AWS SDK for JavaScript v3 region configuration resolution path, specifically in the @smithy/config-resolver package. A region value supplied through application configuration, environment variables, profiles, or programmatic client construction may not have been constrained as strictly as intended. The advisory describes the change as a defense-in-depth enhancement, and the low CVSS score indicates limited direct impact; exploitation would generally require an attacker to influence the region parameter consumed by an application rather than remotely compromise the SDK by itself.

Why it matters to the business

The primary business risk is misuse or unexpected behavior in applications that construct AWS service clients from untrusted or weakly controlled configuration. In practical terms, this could cause requests to be directed unexpectedly, produce service failures, or contribute to a larger attack chain where configuration injection is already possible. There is no indication that this issue is in CISA KEV, used in ransomware campaigns, or publicly mature as an exploit, so remediation should be handled through normal dependency patching rather than emergency incident response unless the application accepts AWS region values from users or external systems.

How an attack unfolds

An attacker would first need a way to control or influence the AWS region value used by an application relying on the vulnerable @smithy/config-resolver versions. That influence could come from user-supplied input, poisoned configuration, modified environment variables, manipulated deployment settings, or compromised profile/config files. The application then initializes an AWS SDK for JavaScript v3 client using the attacker-controlled region value. Because the affected package did not validate the region value as defensively as later versions, the crafted value may be accepted and propagated into SDK client configuration or request construction. The likely result is abnormal request routing, application errors, or a supporting condition for another vulnerability or misconfiguration; this advisory does not indicate a standalone remote code execution, credential theft, or privilege escalation primitive.

How to fix it

Upgrade @smithy/config-resolver to version 4.4.0 or later. For Debian-packaged affected software, use distribution packages fixed in version 5.17.6-1 for Debian 12, Debian 13, and Debian 14 where applicable. Rebuild and redeploy applications after updating lockfiles and container images so the fixed dependency is actually included at runtime. As an additional mitigation, treat AWS region values as configuration, not user input: allowlist known-good AWS regions, reject unexpected characters, avoid constructing SDK clients directly from untrusted request parameters, and restrict write access to environment variables, AWS shared config files, deployment manifests, and CI/CD secrets.

How to confirm the fix worked

Confirm that dependency resolution shows @smithy/config-resolver version 4.4.0 or later in package-lock.json, npm-shrinkwrap.json, pnpm-lock.yaml, yarn.lock, SBOMs, and built artifacts. For Debian-based deployments, verify that the relevant package is at 5.17.6-1 or later using the system package manager. Run dependency scanners against source repositories, built containers, and deployed images to ensure no vulnerable transitive copy remains. Functionally test application startup and AWS client calls with valid region values, and add negative tests to confirm malformed or unexpected region strings are rejected before they reach SDK client construction.

Typical attack path

1. Identify an application or service using AWS SDK for JavaScript v3 with a vulnerable @smithy/config-resolver dependency.
2. Find a path to influence the AWS region value, such as application input, environment variables, shared config files, CI/CD variables, or deployment configuration.
3. Supply a malformed or unexpected region value.
4. Trigger application functionality that initializes an AWS SDK client or sends AWS API requests using that region value.
5. Observe whether the application makes unexpected requests, fails open, logs sensitive errors, or exhibits behavior useful for a broader attack chain.

How to detect it

There are no public, vulnerability-specific indicators of compromise for this advisory, and no known exploited-in-the-wild status is reported. To assess whether the weakness may have been abused, review application logs for unusual AWS region values, failed AWS SDK client initialization, repeated endpoint or signing errors, and requests where a region value was supplied by a user, API client, webhook, job parameter, or deployment variable. Useful log sources include application logs, API gateway or reverse proxy logs, CI/CD job logs, container runtime logs, serverless function logs, AWS SDK debug logs if enabled, and configuration-management audit trails. Investigate changes to environment variables, AWS shared config files, deployment manifests, and CI/CD variables around the time of abnormal AWS API failures. In AWS telemetry, look for unusual service endpoint usage, repeated SignatureDoesNotMatch or invalid endpoint errors, and unexpected calls to regions not normally used by the application.

What your security team should do

• Prioritize remediation for internet-facing applications, multi-tenant services, CI/CD systems, and any service that accepts or derives AWS region values from external input.
• Upgrade @smithy/config-resolver to 4.4.0 or later and refresh all lockfiles, containers, serverless bundles, and deployed artifacts.
• Search repositories and configuration templates for AWS client construction patterns that pass request parameters or external configuration directly into the region field.
• Add application-level allowlisting for approved AWS regions and reject malformed region values before SDK initialization.
• Review dependency scanning coverage for transitive npm packages so @smithy/config-resolver is detected even when pulled in indirectly through AWS SDK for JavaScript v3 packages.
• Because no known exploited or ransomware use is reported, handle as routine patch management unless local applications expose region selection to untrusted users.