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The described issue is a defense-in-depth enhancement, not a formal CVE. In the AWS SDK for JavaScript v3, the client configuration uses a region string to construct the service endpoint URL (e.g., “s3.us-east-1.amazonaws.com”). An actor with access to the application’s runtime environment (e.g., via environment variables, configuration files, or compromised dependencies) could inject a malformed region value. This region value was not rigorously validated before being used as a host label component in the endpoint URL. A region like “us-east-1..internal” or “us-east-1&evil.com” could result in the SDK generating a nonsensical or potentially malicious endpoint target like “s3.us-east-1..internal.amazonaws.com” or incorporating unexpected characters. While the SDK’s underlying HTTP client would likely fail to resolve such a host, the lack of strict validation allowed for the attempted construction of invalid URLs. This could be misused in complex attack chains involving SSRF or to cause application errors. The patch enforces RFC 3986 host label rules via a regex check, rejecting regions with invalid characters before URL assembly.
Platform: AWS SDK JavaScript
Version: v3 <3.723.0
Vulnerability: Invalid Region Input
Severity: Low
Date: 2025-11-15
Prediction: Already Patched 2025-11-15
What Undercode Say:
npm list @smithy/config-resolver
npm update @aws-sdk/client-s3 @smithy/config-resolver
// Pre-validation example
const region = process.env.AWS_REGION;
if (!/^[a-z0-9-]+$/.test(region)) {
throw new Error('Invalid region format');
}
How Exploit:
export AWS_REGION="us-east-1'--"
// Malicious config injection
const client = new S3Client({ region: ".." });
Protection from this CVE:
Update SDK packages.
Validate runtime configuration.
Follow AWS IAM best practices.
Impact:
Improper API routing.
Potential request failures.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
