Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

CVE-2026-53539

Gravedad CVSS v3.1:
ALTA
Tipo:
CWE-400 Consumo de recursos no controlado (Agotamiento de recursos)
Fecha de publicación:
22/06/2026
Última modificación:
26/06/2026

Descripción

*** Pendiente de traducción *** Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead did it fall back to scanning for ;. For a body that uses ; as the separator and contains no &, every field iteration performed a full failed & scan over the entire remaining buffer before locating the nearby ;. With N semicolon separated fields in a chunk of size B, this yields O(B^2) byte comparisons per chunk. An attacker can submit a small crafted body of the form a;a;a;... and cause the parser to spend seconds of CPU per request. A handful of concurrent requests can exhaust worker processes. This vulnerability is fixed in 0.0.30.

Productos y versiones vulnerables

CPE Desde Hasta
cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:python:*:* 0.0.30 (excluyendo)