CVE-2026-48776: LangGraph SDK has unsafe URL path construction

langgraph-sdk constructs HTTP request paths for resource operations by interpolating caller-supplied identifier values into URL templates. Without sanitization of those values, identifiers that contain characters with special meaning in URL paths could cause the resulting request to address a different resource (and potentially a different resource type) than the SDK method’s call site indicates. In deployments where the SDK receives identifier values that originate from untrusted sources, this could result in unintended access, modification, or deletion of resources beyond the calling user’s authorization scope.

This issue is most consequential in deployments that:

• forward end-user-supplied values directly into SDK identifier parameters without first validating them against an expected format (such as a UUID), and
• rely on URL-prefix-based authorization at an upstream layer (reverse proxy, edge gateway, WAF), where the authorization decision is made on the SDK call’s intended path rather than on the final delivered request path.

There have no evidence of this behavior being triggered in the wild. This change is intended to reduce the surface available when caller-supplied identifier values originate from untrusted sources.