Open WebUI Unauthenticated Multipart Boundary Denial of Service (DoS) Vulnerability
A Denial of Service (DoS) vulnerability exists in open-webui/open-webui version 0.3.21. This vulnerability affects multiple endpoints, including /ollama/models/upload, /audio/api/v1/transcriptions, and /rag/api/v1/doc. The application processes multipart boundaries without authentication, leading to resource exhaustion. By appending additional characters to the multipart boundary, an attacker can cause the server to parse each byte of the boundary, ultimately leading to service unavailability. This vulnerability can be exploited remotely, resulting in high CPU and memory usage, and rendering the service inaccessible to legitimate users.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | open-webui | <= 0.3.21 | no fix |
| Python (PyPI) | open-webui | <= 0.3.21 | no fix |
References
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-400- Platform
- npm, Python (PyPI)
- Package
open-webui- Disclosed
- 20.03.2025
- Updated
- 11.10.2026 12:19
Sources and licenses
OSV / GitHub Advisory Database - GHSA-5ccf-884p-4jjq - CC BY 4.0
Vulnerability history: open-webui
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 10
- First → latest
- 03.2025 05.2026
- Without a fix
- 3
- Exploited in attacks
- 0
Severity breakdown
- High 9
- Medium 1
Disclosures per year
- 2025: 6
- 2026: 4
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Open WebUI Unauthenticated Multipart Boundary Denial of Service (DoS) Vulnerability this entry
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