Executive brief
Open WebUI is a user-friendly interface for AI models. The application fails to validate the length of email and password inputs during sign-in, allowing attackers to submit extremely large payloads that exhaust server resources (CPU, memory, disk). This causes the service to become unavailable to legitimate users without requiring authentication.
Technical details
The vulnerability is an uncontrolled resource consumption (CWE-400) flaw in the authentication endpoint. The sign-in process does not enforce character length limits on email and password fields, allowing attackers to submit arbitrarily large strings. When processed, these oversized payloads exhaust server resources and trigger a denial-of-service condition. The attack is network-reachable and requires no authentication or user interaction. The vulnerable code is located in src/lib/apis/auths/index.ts (lines 113-142). Versions up to and including v0.3.32 are affected across both PyPI and npm distributions.
Affected products
- Open WebUI Open WebUI 0.1.124 through 0.3.32
Timeline
- 2025-03-20: disclosed: Vulnerability published in GitHub Advisory Database and NVD
- 2025-03-21: other: GitHub security team review completed