PT-2026-50734 · Npm · Http-Proxy-Middleware

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CVE-2026-55602

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Published

2026-06-18

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Updated

2026-07-27

CVSS v3.1

8.6

High

VectorAV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Name of the Vulnerable Software and Affected Versions http-proxy-middleware versions 0.16.0 through 2.0.9 http-proxy-middleware versions 3.0.0 through 3.0.5 http-proxy-middleware versions 4.0.0 through 4.0.9
Description An issue exists in the router proxy-table implementation where host+path selectors use unanchored substring matching on request metadata. When a router key contains a /, the getTargetFromProxyTable() function concatenates the Host header and the request URL into a single string and checks if the configured key is a substring of that combined value. This allows an attacker to bypass routing boundaries by providing a crafted Host header that acts as a superstring match for the configured key, potentially routing requests to unintended backends. This affects the createProxyMiddleware() function when configured with host+path rules.
Recommendations Update to version 2.0.10, 3.0.6, or 4.1.0 depending on the major version in use. As a temporary workaround, avoid using host+path selectors in the router configuration of createProxyMiddleware() until the update is applied.

Exploit

Fix

RCE

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Weakness Enumeration

Related Identifiers

CVE-2026-55602
GHSA-64MM-VXMG-Q3VJ
OPENSUSE-SU-2026:21448-1

Affected Products

Http-Proxy-Middleware