GHSA-j965-2qgj-vjmq

What it actually does

This is an improper input validation issue affecting applications that use AWS JavaScript SDK v2-style region configuration and allow the region value to be influenced by untrusted input. A malicious or malformed region string can alter how the SDK constructs service endpoints or selects request destinations, potentially causing requests to be sent to unintended endpoints, fail open/closed in unexpected ways, or expose request metadata depending on the surrounding application logic and network controls. Exploitation requires an attacker-controlled path into the region parameter, so the impact is typically limited to applications that dynamically accept region values from users, requests, configuration APIs, or external metadata.

Why it matters to the business

The most likely business impact is service disruption, misrouted cloud API calls, or leakage of request details if an application lets outside users control the SDK region setting. The severity is relatively low because exploitation depends on unsafe application usage, there is no known public exploit maturity, and it is not listed in CISA KEV or known ransomware campaigns. However, SDKs are often embedded across many services, so organizations should still inventory usage and fix exposed code paths, especially in Debian 12, 13, and 14 packages where fixed version 5.17.6-1 is available.

How an attack unfolds

An attacker first finds an application feature where a region value is accepted from a request, tenant setting, API parameter, environment-backed configuration, or other externally influenced source. They submit a crafted region string containing unexpected characters, invalid region names, or endpoint-influencing content. If the application passes that value directly into the JavaScript SDK v2 region configuration without allowlist validation, the SDK may construct or select an unintended service endpoint. The attacker then observes whether cloud API calls are redirected, fail, disclose error details, or interact with infrastructure outside the intended region or partition. Successful exploitation depends heavily on application design, outbound network access, DNS/proxy behavior, TLS validation, and whether sensitive SDK requests are made after the malicious region is accepted.

How to fix it

Prefer migrating affected JavaScript SDK v2 usage to AWS SDK for JavaScript v3 where practical. For any remaining v2 usage, never pass untrusted input directly into the region parameter. Validate regions using a strict allowlist of approved AWS regions and partitions required by the application, reject empty values and values containing URL metacharacters, path separators, whitespace, control characters, userinfo delimiters, or host-like strings, and avoid dynamically constructing SDK clients from request parameters. Where Debian packages are in scope, update affected Debian 12, Debian 13, and Debian 14 systems to fixed version 5.17.6-1 or later. Add egress controls so application workloads can only reach expected cloud service endpoints. If logs show that sensitive signed requests were sent to unintended infrastructure, rotate affected credentials and review cloud audit logs for unauthorized activity.

How to confirm the fix worked

Confirm dependency and package versions through software inventory, lockfiles, image manifests, and package manager output. For JavaScript applications, search for AWS SDK v2 usage and region assignment patterns such as AWS.config.update, new AWS.Config, new AWS.Service clients, or service constructors that receive a region value. Verify that every region value is derived from trusted configuration or is checked against an explicit allowlist before use. Add negative tests that submit malformed region values containing slashes, schemes, at-signs, dots, whitespace, encoded characters, and overly long strings, and confirm the application rejects them before SDK client creation. For Debian 12, 13, and 14 assets where the affected package mapping applies, confirm installed versions are 5.17.6-1 or later. Review outbound DNS/proxy/firewall telemetry during tests to ensure invalid region values do not produce external network requests.

Typical attack path

1. Identify an application feature or API that accepts or stores a cloud region value.
2. Submit malformed or non-standard region strings instead of a legitimate region such as us-east-1 or eu-west-1.
3. Trigger application functionality that causes AWS JavaScript SDK v2 to create clients or send requests using the supplied region.
4. Observe application errors, timing differences, outbound DNS/HTTP activity, or unexpected service behavior.
5. Refine the region payload to influence endpoint construction or request routing where possible.
6. Use any resulting misrouting, failure mode, or exposed request metadata to support further reconnaissance or disruption.

How to detect it

There are no universal indicators of compromise for this issue because exploitation depends on application-specific region handling and the attacker-controlled value may appear only in application logs. To assess prior exploitation, review application logs, API gateway logs, WAF logs, configuration change logs, and audit trails for malformed region values submitted to endpoints that create or configure cloud clients. Correlate those events with SDK errors, DNS queries, proxy logs, firewall logs, and outbound TLS connections to unexpected hosts at the same time. Look for region strings containing URL schemes, slashes, backslashes, at-signs, colons, dots used as hostnames, encoded delimiters, whitespace, shell metacharacters, or values that are not in the organization's approved region allowlist. Review AWS CloudTrail or equivalent cloud audit logs for unusual API errors, requests from unexpected regions, authentication failures, or activity immediately after malformed region submissions. If threat hunting finds outbound requests carrying signed authorization headers to non-approved infrastructure, treat associated credentials as potentially exposed.

What your security team should do

• Inventory applications, containers, and build artifacts for AWS JavaScript SDK v2 usage and any Debian packages mapped to the affected fixed version.
• Prioritize internet-facing services, APIs, admin portals, and multi-tenant systems where region values can be supplied or modified by users or external integrations.
• Migrate to AWS SDK for JavaScript v3 where feasible; otherwise implement strict region allowlisting before SDK client creation.
• Patch Debian 12, Debian 13, and Debian 14 systems to version 5.17.6-1 or later where the affected package is present.
• Add static analysis or code review checks for user-controlled values passed to SDK region configuration.
• Restrict workload egress to expected cloud service endpoints and monitor for unusual DNS or HTTP requests caused by malformed region values.
• Search historical logs for invalid region errors, unusual SDK endpoint construction, and outbound connections to unexpected hosts around cloud API activity.
• Rotate credentials only if evidence indicates signed SDK requests or sensitive request metadata reached an unintended endpoint.