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.
Metrics
Affected Vendors & Products
References
History
Mon, 29 Jun 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Tue, 23 Jun 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Tue, 23 Jun 2026 00:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Chimurai
Chimurai http-proxy-middleware |
|
| Vendors & Products |
Chimurai
Chimurai http-proxy-middleware |
Mon, 22 Jun 2026 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody` | |
| Weaknesses | CWE-93 | |
| References |
| |
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-06-22T20:07:05.034Z
Updated: 2026-06-23T12:21:14.668Z
Reserved: 2026-06-16T23:31:22.444Z
Link: CVE-2026-55603
Updated: 2026-06-23T12:21:10.631Z
No data.