FlowiseAI Flowise S3 Document Loader S3.ts path traversal

An attacker who can influence object keys in a configured S3 source (e.g., by uploading objects with crafted keys to the bucket) can cause Flowise to write files outside the loader workspace. The object key is externally controlled through S3 bucket contents or a configured S3-compatible object store, and no final path containment check ensures the resolved path remains below the intended temp directory before write or cleanup [ref_id=1]. This is a path traversal vulnerability [CWE-22] combined with external control of file name or path [CWE-73].

The vulnerable function resides in `packages/components/nodes/documentloaders/S3/S3.ts` (S3Directory / S3File document loader). The code derives local temporary file paths from attacker-controlled S3 object keys without constraining them to the intended temporary directory, and object keys containing traversal sequences can escape the loader temp directory [ref_id=1].

The advisory recommends normalizing each object key to a safe basename or explicitly rejecting absolute/traversal paths, and after joining paths, resolving both base and target and enforcing `target.relative_to(base)`. Recursive cleanup on paths influenced by untrusted object names should be avoided [ref_id=1]. No patch has been published by the vendor.