CVE-2026-55602: CWE-20: Improper Input Validation in chimurai http-proxy-middleware
http-proxy-middleware is node.js http-proxy middleware. From 0.16.0 until 2.0.10, 3.0.6, and 4.1.0, http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configured host+path key can still route a request to an unintended backend. This vulnerability is fixed in 2.0.10, 3.0.6, and 4.1.0.
AI Analysis
Technical Summary
http-proxy-middleware versions before 2.0.10, 3.0.6, and 4.1.0 improperly validate input in the host+path router proxy-table entries by using unanchored substring matching on the Host header. This allows an attacker to craft a Host header that is a superstring match of a configured host+path key, causing the request to be routed to an unintended backend. This is a CWE-20 (Improper Input Validation) and CWE-187 (Partial Comparison) vulnerability. The issue is fixed in versions 2.0.10, 3.0.6, and 4.1.0.
Potential Impact
An attacker can manipulate the Host header to cause requests to be routed incorrectly to unintended backend servers. This could lead to unauthorized access or information disclosure depending on the backend configuration. The vulnerability does not require privileges or user interaction and is exploitable remotely over the network.
Mitigation Recommendations
Upgrade http-proxy-middleware to version 2.0.10, 3.0.6, or 4.1.0 or later where this vulnerability is fixed. No other mitigation is indicated by the vendor advisory. Patch status is confirmed fixed in these versions.
CVE-2026-55602: CWE-20: Improper Input Validation in chimurai http-proxy-middleware
Description
http-proxy-middleware is node.js http-proxy middleware. From 0.16.0 until 2.0.10, 3.0.6, and 4.1.0, http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configured host+path key can still route a request to an unintended backend. This vulnerability is fixed in 2.0.10, 3.0.6, and 4.1.0.
CVSS v4.0
Score 6.9medium
Affected software
pkg:npm/http-proxy-middlewareRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
http-proxy-middleware versions before 2.0.10, 3.0.6, and 4.1.0 improperly validate input in the host+path router proxy-table entries by using unanchored substring matching on the Host header. This allows an attacker to craft a Host header that is a superstring match of a configured host+path key, causing the request to be routed to an unintended backend. This is a CWE-20 (Improper Input Validation) and CWE-187 (Partial Comparison) vulnerability. The issue is fixed in versions 2.0.10, 3.0.6, and 4.1.0.
Potential Impact
An attacker can manipulate the Host header to cause requests to be routed incorrectly to unintended backend servers. This could lead to unauthorized access or information disclosure depending on the backend configuration. The vulnerability does not require privileges or user interaction and is exploitable remotely over the network.
Mitigation Recommendations
Upgrade http-proxy-middleware to version 2.0.10, 3.0.6, or 4.1.0 or later where this vulnerability is fixed. No other mitigation is indicated by the vendor advisory. Patch status is confirmed fixed in these versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-16T23:18:03.170Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39735deed863c81e3962f9
Added to database: 06/22/2026, 17:39:41 UTC
Last enriched: 06/29/2026, 21:54:42 UTC
Last updated: 08/05/2026, 12:41:16 UTC
Views: 68
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