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5 vulnerabilities by @fastify/http-proxy
CVE-2026-120213 (GCVE-0-2026-120213)
Vulnerability from cvelistv5 – Published: 2026-11-02 10:15 – Updated: 2026-11-02 17:05
VLAI
EPSS
VEX
Title
@fastify/http-proxy vulnerable to prefix escape via decoded route parameters
Summary
@fastify/http-proxy is a Fastify plugin that proxies HTTP requests to an upstream server under a configured prefix. In versions 9.0.0 through 11.6.5, when an application uses parameterized prefix and rewritePrefix options to pin clients to a fixed upstream path, the plugin substitutes URL-decoded route parameters into rewritePrefix without re-encoding them. A parameter value that encodes a path separator together with a fragment or query delimiter therefore decodes into real separators and delimiters that inject extra upstream path segments and strip the mandatory suffix the rewritePrefix was meant to enforce, without using any dot-dot traversal. An unauthenticated remote attacker can use this to reach upstream locations outside the intended prefix, leading to path-restriction bypass and, depending on the upstream, server-side request forgery or authorization bypass in the proxied service. The issue is fixed in @fastify/http-proxy 11.6.6, and users should upgrade to 11.6.6 or later. There is no workaround other than upgrading.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-02 17:04 UTC
CWE
Assigner
openjs
CNA
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
9.0.0 , < 11.6.6
(semver)
Unaffected: 11.6.6 (semver) |
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CVE-2026-120214 (GCVE-0-2026-120214)
Vulnerability from cvelistv5 – Published: 2026-11-02 10:07 – Updated: 2026-11-02 17:09
VLAI
EPSS
VEX
Title
@fastify/http-proxy vulnerable to prefix escape via percent-encoded backslash dot-segments
Summary
@fastify/http-proxy is a Fastify plugin that proxies HTTP requests to an upstream server under a configured prefix. In versions 11.6.0 through 11.6.2, the destination validation normalizes literal backslashes before it percent-decodes the request path, so a path that encodes its backslashes and dot-segments survives the dot-segment check and is only turned into backslash and double-dot sequences after that check has passed. When the upstream resolves on a platform that treats a backslash as a path separator, the forwarded request walks out of the configured proxy prefix and reaches a sibling location on the upstream. An unauthenticated remote attacker can use this to retrieve upstream resources outside the intended prefix, so the impact is confidentiality only, and exploitation depends on the upstream's path handling. The issue is fixed in @fastify/http-proxy 11.6.3, and users should upgrade to 11.6.3 or later. This is a follow-up to the earlier prefix-escape fix, which did not account for the encoded-backslash form.
Severity
5.9 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-02 17:09 UTC
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
openjs
CNA
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
11.6.0 , < 11.6.3
(semver)
Unaffected: 11.6.3 (semver) |
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CVE-2026-85124 (GCVE-0-2026-85124)
Vulnerability from cvelistv5 – Published: 2026-09-03 10:51 – Updated: 2026-09-03 12:32
VLAI
EPSS
VEX
Title
@fastify/http-proxy vulnerable to prefix escape via backslash dot-segments
Summary
@fastify/http-proxy versions before 11.6.2 do not validate proxied HTTP request paths for backslash based dot-segments before forwarding them to the configured upstream. The plain HTTP request handler skips the destination validation that the WebSocket path performs, and the underlying reply-from library only rejects forward-slash traversal, so a request containing backslash dot-segments can escape the boundary set by the prefix and rewritePrefix options. An unauthenticated network attacker can use this to reach upstream paths that were meant to stay hidden behind the proxy, resulting in disclosure of internal endpoints. This is a path traversal issue (CWE-22). Users should upgrade to @fastify/http-proxy 11.6.2 or later.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-03 12:31 UTC
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
openjs
CNA
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
0 , < 11.6.2
(semver)
Unaffected: 11.6.2 (semver) |
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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
openjs
CNA
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
0 , < 11.6.0
(semver)
Unaffected: 11.6.0 (semver) |
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CVE-2026-15631 (GCVE-0-2026-15631)
Vulnerability from cvelistv5 – Published: 2026-07-18 12:46 – Updated: 2026-07-20 15:15
VLAI
EPSS
VEX
Title
@fastify/http-proxy vulnerable to prefix escape via WebSocket path traversal
Summary
Impact: @fastify/http-proxy versions from 9.4.0 up to and including 11.5.0 fail to validate the resolved WebSocket destination path against the configured rewrite prefix. The WebSocket routing path in WebSocketProxy.findUpstream resolves the destination via the WHATWG URL constructor, which collapses dot segments, so a crafted upgrade request with path traversal sequences can escape the rewrite prefix and reach upstream endpoints that were not meant to be exposed by the proxy. This is a variant of CVE-2021-21322 in a code path that never went through the HTTP fix in fastify/reply-from. Exploitation requires a non-normalizing WebSocket client, since browsers and the ws package normalize the request path before sending, but raw HTTP clients or downstream proxies that forward the request target unchanged make the attack reachable in production topologies.
Patches: upgrade to @fastify/http-proxy 11.6.0.
Workarounds: none.
Severity
8.7 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-20 15:15 UTC
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
openjs
CNA
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| @fastify/http-proxy | @fastify/http-proxy |
Affected:
9.4.0 , < 11.6.0
(semver)
Unaffected: 11.6.0 (semver) |
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