CVE-2026-55446: Langflow: Unauthenticated DoS through multipart form boundary file upload

June 19, 2026

An attacker can send a /api/v1/files/upload/ request without any authentication token/cookies and abuse a very long multipart form boundary to make the langflow app unusable for all users for an indefinite amount of time.

References

github.com/advisories/GHSA-qwqc-p3q8-wcg9
github.com/langflow-ai/langflow/blob/v1.0.18/src/backend/base/langflow/api/v1/files.py
github.com/langflow-ai/langflow/pull/3923
github.com/langflow-ai/langflow/security/advisories/GHSA-qwqc-p3q8-wcg9
nvd.nist.gov/vuln/detail/CVE-2026-55446

Code Behaviors & Features

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