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. Patches: upgrade to @fastify/http-proxy 11.6.0. Workarounds: none.

CVSS v3 10.0 CRITICAL

10.0^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.8

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://cna.openjsf.org/security-advisories.html	Vendor Advisory
https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-mx7v-qhg9-2mvv	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:fastify:fastify\/http-proxy:*:*:*:*:*:node.js:*:*

History

28 Jul 2026, 15:39

Type	Values Removed	Values Added
References	~~() https://cna.openjsf.org/security-advisories.html -~~	() https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References	~~() https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-mx7v-qhg9-2mvv -~~	() https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-mx7v-qhg9-2mvv - Vendor Advisory
CPE		cpe:2.3:a:fastify:fastify\/http-proxy::::::node.js::*
First Time		Fastify Fastify fastify\/http-proxy

18 Jul 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-18 14:17

Updated : 2026-07-28 15:39

NVD link : CVE-2026-16117

Mitre link : CVE-2026-16117

CVE.ORG link : CVE-2026-16117

JSON object : View

Products Affected

fastify

fastify\/http-proxy

CWE

CWE-20

Improper Input Validation

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