high8.6
CVE-2026-55602
http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | http-proxy-middleware | >= 4.0.0, < 4.1.0 | 4.1.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Chimurai | Http-Proxy-Middleware | from 0.16.0 before 2.0.10 from 3.0.0 before 3.0.6 from 4.0.0 before 4.1.0 |