Langflow: Unauthenticated file upload leads to DoS (space exhaustion) and information leak
- Product
- langflow
- CVE
- CVE-2026-55450
- Affected
- langflow < 1.9.1
- Fixed in
- 1.9.1
Last verified against sources: October 26, 2026
Am I affected?
langflow: affected langflow < 1.9.1. Fixed in 1.9.1.
- Check your version: run
pip show langflow. Versions < 1.9.1 of langflow are affected. [1]
What to do now
- Upgrade to the fixed version: run
pip install --upgrade "langflow>=1.9.1"(first patched version 1.9.1). [1] - Upgrade to 1.9.1 or later. [1]
General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.
What happened
- Unauthenticated users can upload any amount of data to the server without any limitations. [1]
- This can lead to space exhaustion on the server. [1]
- In adition, in the response, the absolute path of the uploaded file is reported to the attacker, which is an information leak that can assist in chaining other primitives. [1]
Impact
What was done
- Fixed in 1.9.1 via PR #12831. [1]
- The deprecated POST /api/v1/upload/{flow_id} endpoint now uses the get_flow dependency, requiring an authenticated user and flow ownership (returns 404 for missing or cross-user flows), and enforces the max_file_size_upload limit (HTTP 413) — closing the unauthenticated upload and disk-exhaustion vectors. [1]
Sources
- GHSA-x223-p2gf-v735 — GitHub Advisory Database
Every statement above was checked against these sources before publishing. Spotted an error? Tell us and we will correct it with a dated note.
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[CVE-2026-55450] Langflow: Unauthenticated file upload leads to DoS (space exhaustion) and information leak
Product: langflow | Affected: langflow < 1.9.1 | Fixed in: 1.9.1
Summary: Unauthenticated users can upload any amount of data to the server without any limitations.
Source & remediation on AgentArmorHQ: https://agentarmorhq.com/incidents/2026/06/cve-2026-55450-langflowCorrections
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