Http Proxy Middleware

http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with handlerFormDataBodyData(), which interpolates each req.body key and value directly into the multipart wire format without neutralizing CR/LF. A \r\n inside a value (or key) lets an attacker close the current part and inject an entirely new form part. Because the proxy's own body parser saw a single opaque value, any gateway-side policy or validation performed on req.body is evaluated against a different set of fields than the upstream backend ultimately parses a request/parameter desynchronization across the trust boundary. This vulnerability is fixed in 3.0.7 and 4.1.1.

Published: 2026-06-22T20:07:05.034Z
Updated: 2026-06-23T12:21:14.668Z

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.

Published: 2026-06-22T15:58:08.699Z
Updated: 2026-06-23T14:18:06.403Z

In http-proxy-middleware before 2.0.9 and 3.x before 3.0.5, fixRequestBody proceeds even if bodyParser has failed.

Published: 2025-04-15T00:00:00.000Z
Updated: 2025-04-15T03:54:38.610Z

In http-proxy-middleware before 2.0.8 and 3.x before 3.0.4, writeBody can be called twice because "else if" is not used.

Published: 2025-04-15T00:00:00.000Z
Updated: 2025-04-15T03:55:51.136Z

Versions of the package http-proxy-middleware before 2.0.7, from 3.0.0 and before 3.0.3 are vulnerable to Denial of Service (DoS) due to an UnhandledPromiseRejection error thrown by micromatch. An attacker could kill the Node.js process and crash the server by making requests to certain paths.

Published: 2024-10-19T05:00:04.056Z
Updated: 2026-08-02T15:25:24.640Z