CVE-2026-3635
fastify: request.protocol and request.host Spoofable via X-Forwarded-Proto/Host from Untrusted Connections
描述
## 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.
如何修補 CVE-2026-3635
要修補 CVE-2026-3635,請將受影響套件升級到下列已修補版本。
- —升級至 5.8.3 或更新版本
CVE-2026-3635 正在被利用嗎?
低 — EPSS 為 0.1%,目前沒有觀察到大規模利用活動。
受影響套件(1)
- from 0, < 5.8.3
CVSS 分數
| 來源 | 版本 | 嚴重程度 | 向量 |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.1 | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N |