CVE-2026-55603
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.
- CVSS 3.1
- 7.5
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N - EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 20% of CVEs (scores of 2026-10-25)
- CWE
- CWE-93
- Published
- Modified
- Record from
- the NVD, synced
Affected
- chimurai:http-proxy-middleware
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-gcq2-9pq2-cxqm | npm | http-proxy-middleware | >=3.0.4 <3.0.7 | 3.0.7 |
| GHSA-gcq2-9pq2-cxqm | npm | http-proxy-middleware | >=4.0.0 <4.1.1 | 4.1.1 |