Denial of service (DoS) via deformation `multipart/form-data` boundary
Summary
When parsing form data, python-multipart skips line breaks (CR \r or LF \n) in front of the first boundary and any tailing bytes after the last boundary. This happens one byte at a time and emits a log event each time, which may cause excessive logging for certain inputs.
An attacker could abuse this by sending a malicious request with lots of data before the first or after the last boundary, causing high CPU load and stalling the processing thread for a significant amount of time. In case of ASGI application, this could stall the event loop and prevent other requests from being processed, resulting in a denial of service (DoS).
Impact
Applications that use python-multipart to parse form data (or use frameworks that do so) are affected.
Original Report
This security issue was reported by:
- GitHub security advisory in Starlette on October 30 by @Startr4ck
- Email to
python-multipartmaintainer on October 3 by @mnqazi
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | python-multipart | < 0.0.18 | 0.0.18 |
Referencias
- https://github.com/Kludex/python-multipart/security/advisories/GHSA-59g5-xgcq-4qw3
- https://nvd.nist.gov/vuln/detail/CVE-2024-53981
- https://github.com/Kludex/python-multipart/commit/c4fe4d3cebc08c660e57dd709af1ffa7059b3177
- https://github.com/Kludex/python-multipart
- https://pypi.org/project/python-multipart
- https://github.com/advisories/GHSA-59g5-xgcq-4qw3
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Debilidad (CWE)
CWE-770- Plataforma
- Python (PyPI)
- Paquete
python-multipart- Publicada
- 02.12.2024
- Actualizado
- 11.10.2026 15:17
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2026-1851 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-59g5-xgcq-4qw3 - CC BY 4.0
Historial de vulnerabilidades: python-multipart
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 9
- Primera → última
- 02.2024 06.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 5
- Media 1
- Baja 3
Divulgaciones por año
- 2024: 2
- 2025: 0
- 2026: 7
-
Denial of service (DoS) via deformation `multipart/form-data` boundary esta entrada
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