fastify: request.protocol and request.host Spoofable via X-Forwarded-Proto/Host from Untrusted Connections

TRUNG BÌNH 6.1CVE-2026-3635 · GHSA-444r-cwp2-x5xf · Công bố 23/03/2026 · cập nhật 17/06/2026

Tóm tắt nhanh

CVE-2026-3635 là lỗ hổng mức TRUNG BÌNH (CVSS 6.1) ảnh hưởng fastify (fastify), fastify.
Xác suất bị khai thác trong 30 ngày tới (EPSS): 0.16%, cao hơn 5.3% các lỗ hổng khác.
Cách xử lý: cập nhật lên 5.8.3 hoặc mới hơn.

Gói / sản phẩm	Phiên bản bị ảnh hưởng	Phiên bản đã vá
fastify fastify	`< 5.8.3`	`5.8.3`
fastify npm	`< 5.8.3`	`5.8.3`

Mô tả

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.

Mô tả của NVD

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.