fastify: request.protocol and request.host Spoofable via X-Forwarded-Proto/Host from Untrusted Connections
Summary
When trustProxy is configured with a restrictive trust function (e.g., a specific IP like trustProxy: '10.0.0.1', a subnet, a hop count, or a custom function), the request.protocol and request.host getters read X-Forwarded-Proto and X-Forwarded-Host headers from any connection — including connections from untrusted IPs. This allows an attacker connecting directly to Fastify (bypassing the proxy) to spoof both the protocol and host seen by the application.
Affected Versions
fastify <= 5.8.2
Impact
Applications using request.protocol or request.host for security decisions (HTTPS enforcement, secure cookie flags, CSRF origin checks, URL construction, host-based routing) are affected when trustProxy is configured with a restrictive trust function.
When trustProxy: true (trust everything), both host and protocol trust all forwarded headers — this is expected behavior. The vulnerability only manifests with restrictive trust configurations.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | fastify | < 5.8.3 | 5.8.3 |
Referencias
- https://github.com/fastify/fastify/security/advisories/GHSA-444r-cwp2-x5xf
- https://nvd.nist.gov/vuln/detail/CVE-2026-3635
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify
- https://github.com/fastify/fastify/releases/tag/v5.8.3
- https://www.cve.org/CVERecord?id=CVE-2026-3635
- Vector CVSS
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N- Debilidad (CWE)
CWE-348- Plataforma
- npm
- Paquete
fastify- Publicada
- 25.03.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-444r-cwp2-x5xf - CC BY 4.0
Historial de vulnerabilidades: fastify
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 16
- Primera → última
- 07.2018 09.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 8
- Media 7
- Baja 1
Divulgaciones por año
- 2018: 1
- 2019: 0
- 2020: 1
- 2021: 0
- 2022: 2
- 2023: 0
- 2024: 0
- 2025: 1
- 2026: 11
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fastify: request.protocol and request.host Spoofable via X-Forwarded-Proto/Host from Untrusted Connections esta entrada
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