CVE-2026-16117
Impact: @fastify/http-proxy versions up to and including 11.5.0 fail to rewrite the request prefix when the prefix segment is URL-encoded. Fastify's router URL-decodes paths for route matching, but request.url retains the original encoded form, and the prefix-rewrite step uses a literal string replace against the decoded prefix. A request that encodes one or more characters of the configured prefix therefore matches the route but skips the rewrite, so the raw encoded path is forwarded to the upstream unchanged. The upstream then decodes the path and serves it, letting an attacker reach upstream paths that the proxy was configured to hide via rewritePrefix, including internal or administrative endpoints.
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Patches: upgrade to @fastify/http-proxy 11.6.0.
Workarounds: none.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
- Puntuación base: 10
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.44%
- Percentil entre todas las CVEs puntuadas: 36
- 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 access95 % - Impacto principal
T1565.002Transmitted Data Manipulationimpact85 % - Impacto secundario
T1552.007Container APIcredential access80 %
Vulnerabilidad crítica en proxy HTTP (AV:N, PR:N, UI:N) que permite eludir restricciones de prefijo mediante URL-encoding para alcanzar endpoints internos/administrativos ocultos, causando acceso a datos sensibles y potencial manipulación.
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 (1)
CWE
- CWE-20
Referencias
JSON original (NVD)
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