CVE-2024-47874
Starlette is an Asynchronous Server Gateway Interface (ASGI) framework/toolkit. Prior to version 0.40.0, Starlette treats `multipart/form-data` parts without a `filename` as text form fields and buffers those in byte strings with no size limit. This allows an attacker to upload arbitrary large form fields and cause Starlette to both slow down significantly due to excessive memory allocations and copy operations, and also consume more and more memory until the server starts swapping and grinds to a halt, or the OS terminates the server process with an OOM error.
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Uploading multiple such requests in parallel may be enough to render a service practically unusable, even if reasonable request size limits are enforced by a reverse proxy in front of Starlette. This Denial of service (DoS) vulnerability affects all applications built with Starlette (or FastAPI) accepting form requests. Verison 0.40.0 fixes this issue.
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Puntuación base: 8.7
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.65%
- Percentil entre todas las CVEs puntuadas: 50
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access85 % - Impacto principal
T1499.004Application or System Exploitationimpact90 %
AV:N/PR:N/UI:N indica explotación remota sin autenticación; CWE-770 (asignación excesiva de recursos) + descripción de DoS por carga de campos form sin límite = T1499.004 (consumo de memoria/recursos hasta indisponibilidad)
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (2)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-770
Referencias
JSON original (NVD)
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"value": "Starlette es un conjunto de herramientas/marco de interfaz de puerta de enlace de servidor asincrónico (ASGI). Antes de la versión 0.40.0, Starlette trata las partes `multipart/form-data` sin un `filename` como campos de formulario de texto y las almacena en búfer en cadenas de bytes sin límite de tamaño. Esto permite a un atacante cargar campos de formulario arbitrarios de gran tamaño y hacer que Starlette se ralentice significativamente debido a asignaciones de memoria excesivas y operaciones de copia, y también consuma cada vez más memoria hasta que el servidor comienza a intercambiar y se detiene, o el sistema operativo finaliza el proceso del servidor con un error OOM. Cargar múltiples solicitudes de este tipo en paralelo puede ser suficiente para dejar un servicio prácticamente inutilizable, incluso si se aplican límites de tamaño de solicitud razonables mediante un proxy inverso frente a Starlette. Esta vulnerabilidad de denegación de servicio (DoS) afecta a todas las aplicaciones creadas con Starlette (o FastAPI) que aceptan solicitudes de formulario. La versión 0.40.0 corrige este problema."
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