CVE-2026-55602: CWE-20: Improper Input Validation in chimurai http-proxy-middleware
http-proxy-middleware versions prior to 2.0.10, 3.0.6, and 4.1.0 have an improper input validation vulnerability in the host+path router proxy-table entries. The implementation uses unanchored substring matching on the Host header, allowing crafted Host headers that partially match configured keys to route requests to unintended backends. This vulnerability has a medium severity with a CVSS score of 6.9. Fixes are available in versions 2.0.10, 3.0.6, and 4.1.0.
AI Analysis
Technical Summary
The http-proxy-middleware Node.js package 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 attacker-controlled Host headers. 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. The issue is classified under CWE-20 (Improper Input Validation) and CWE-187 (Partial Comparison). The vulnerability 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 data leakage depending on the backend configuration. The vulnerability does not require privileges or user interaction and has a network attack vector. The CVSS 4.0 base score is 6.9 (medium severity). There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrading to http-proxy-middleware versions 2.0.10, 3.0.6, or 4.1.0 or later fully mitigates this vulnerability. Patch status is confirmed by the version fixes stated in the advisory. No additional vendor advisory content is provided, so check the official chimurai project releases for the latest updates.
CVE-2026-55602: CWE-20: Improper Input Validation in chimurai http-proxy-middleware
Description
http-proxy-middleware versions prior to 2.0.10, 3.0.6, and 4.1.0 have an improper input validation vulnerability in the host+path router proxy-table entries. The implementation uses unanchored substring matching on the Host header, allowing crafted Host headers that partially match configured keys to route requests to unintended backends. This vulnerability has a medium severity with a CVSS score of 6.9. Fixes are available in versions 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
The http-proxy-middleware Node.js package 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 attacker-controlled Host headers. 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. The issue is classified under CWE-20 (Improper Input Validation) and CWE-187 (Partial Comparison). The vulnerability 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 data leakage depending on the backend configuration. The vulnerability does not require privileges or user interaction and has a network attack vector. The CVSS 4.0 base score is 6.9 (medium severity). There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrading to http-proxy-middleware versions 2.0.10, 3.0.6, or 4.1.0 or later fully mitigates this vulnerability. Patch status is confirmed by the version fixes stated in the advisory. No additional vendor advisory content is provided, so check the official chimurai project releases for the latest updates.
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: 06/22/2026, 17:54:44 UTC
Last updated: 06/23/2026, 01:50:01 UTC
Views: 7
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