GHSA-79ph-745m-6wxq
MEDIUMLangflow: Path Traversal in Knowledge Bases API via Creation Endpoint
Blast Radius
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Description
Summary
Langflow is vulnerable to Path Traversal in the Knowledge Bases API (POST /api/v1/knowledge_bases). This occurs because user-supplied knowledge base names are used directly to create file paths without proper sanitization or containment checks. An authenticated attacker can exploit this flaw to create directories and write files anywhere on the server's filesystem.
Details
The vulnerability exists in the create_knowledge_base function within src/backend/base/langflow/api/v1/knowledge_bases.py.
This function constructs file paths directly from the user-supplied name field without sanitization. The value is concatenated with the user's base directory and passed directly to kb_path.mkdir(). Immediately following the directory creation, the application writes embedding_metadata.json and schema.json into this attacker-controlled path.
PoC (Proof of Concept)
For the Create endpoint, an attacker can supply traversal sequences or absolute paths in the name field:
../victim_user/evil_kb
or
/tmp/pwned
This forces kb_path.mkdir() to create directories and write specific application files (embedding_metadata.json and schema.json) at any reachable path on the server.
Impact
Any Langflow instance exposing this endpoint to authenticated users is vulnerable. This exposes the server to:
- Cross-user data compromise: Creation of directories and files within another tenant's knowledge base space.
- Arbitrary filesystem manipulation: Directory creation at any path on the server where the application has write permissions (e.g.,
/app/data). - Data overwrite: Overwriting existing
embedding_metadata.jsonandschema.jsonfiles in attacker-targeted paths, potentially corrupting existing knowledge bases.
Fixes
The issue was addressed in PR #12337. The fix introduces the _validate_kb_path_containment() helper function, which uses Path.is_relative_to() instead of startswith() to enforce strict path boundaries and prevent prefix-ambiguity bugs. This helper is applied before any filesystem operations. Regression tests were added to verify that traversal payloads return a 403 Forbidden.
Acknowledgements
Thanks to the security researchers who responsibly disclosed this vulnerability:
- @ddlxstudio
- @nekros1xx
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | langflow | all versions | 1.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for langflow. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update langflow to 1.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-79ph-745m-6wxq is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-79ph-745m-6wxq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-79ph-745m-6wxq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-79ph-745m-6wxq in your dependencies?
O3 detects GHSA-79ph-745m-6wxq across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.