A flaw in Node.js HTTP client can cause a request desynchronization for Node.js-based forwarding proxies that rebuild outbound headers from the visible `IncomingMessage` headers while piping the original body to a reused backend connection. Node.js can omit headers beyond `maxHeadersCount` / `maxHeaderPairs` from `req.headers`, `req.rawHeaders`, and `req.headersDistinct`, while still using those omitted headers internally for HTTP message framing. In particular, `Content-Length` can be hidden from userland while the request body is still delivered. This vulnerability affects all supported release lines: **Node.js 22**, **Node.js 24**, and **Node.js 26**.
| Version | Type | Source | Base | Exp | Imp |
|---|---|---|---|---|---|
| 3.0 | Primary | cve.org | 3.7 | — | — |
| 3.0 | Primary | cve.org | 3.7 | — | — |
| 3.0 | Secondary | NVD | 3.7 | 2.2 | 1.4 |
| 3.0 | Secondary | ENISA EUVD | 3.7 | — | — |