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Activamente explotadaCVSS 6.5 · MEDIUM

CVE-2026-48710Bypass de autenticación por encabezado Host en Starlette

Kludex Starlette contains a HTTP request/response smuggling vulnerability that could allow attackers to inject paths into the host part, prepending the actual path leading to issues such as authentication bypass when the authentication depends on the reconstructed URL’s path. This vulnerability could be chaned with CVE-2026-42271.

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Análisis

Starlette presenta una vulnerabilidad que permite manipular la reconstrucción de rutas mediante encabezados Host malformados, lo que facilita el bypass de controles de seguridad y autenticación. Este fallo está siendo explotado activamente en ataques reales para evadir middleware que valida el acceso basado en la URL solicitada. Se recomienda actualizar inmediatamente a la versión 1.0.1 o superior para asegurar la validación correcta de los encabezados HTTP.

Roles relevantes

PythonBackendciberseguridad

Severidad

Puntaje: 6.5(MEDIUM)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: UNCHANGED
C: LOW
I: LOW
A: NONE
Tipo de falla (CWE): CWE-444CWE-1289

CISA KEV

Agregada al KEV: 2026-09-02
Fecha límite federal: 2026-09-16
Uso conocido en ransomware: Unknown
Acción requerida

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

EPSS

Probabilidad de explotación (próx. 30 días): 0.0210 (2.1%)
Percentil: 80.4%
EPSS: 2026-09-02

Afecta

encode:starlette

Descripción técnica

Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header could make `request.url.path` differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on `request.url` (rather than the raw `scope` path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the `Host` header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing `request.url` and falls back to `scope["server"]` for malformed values.

Publicada: 26/5/2026, 22:16:44
Última modificación: 2/9/2026, 18:19:22

Referencias

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