CVE-2026-16117 (GCVE-0-2026-16117)
Vulnerability from cvelistv5 – Published: 2026-07-18 13:08 – Updated: 2026-07-20 15:14
VLAI
EPSS
VEX
Title
@fastify/http-proxy vulnerable to prefix escape via URL-encoded characters
Summary
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.
Severity
10 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-20 15:14 UTC
CWE
- CWE-20 - Improper Input Validation
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
0 , < 11.6.0
(semver)
Unaffected: 11.6.0 (semver) |
guessed |
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