CVE-2026-55603 - http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`

CVE-2026-55603 - http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`

https://cvefeed.io/rssfeed/latest.atom / Tue, 06/23/2026 - 01:01
CVE ID :CVE-2026-55603
Published : June 22, 2026, 8:07 p.m. | 1 hour, 33 minutes ago
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.
Severity: 0.0 | NA
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