{"id":"CVE-2026-55603","revision":"b1d2ee9444fd4a1b910500fbc9e5adb9","records":[{"revision":"b1d2ee9444fd4a1b910500fbc9e5adb9","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-55603","aliases":[],"title":"http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`","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.","state":0,"publishedAt":"2026-06-22T20:07:05.034+00:00","modifiedAt":"2026-06-23T12:21:14.668+00:00","affected":[{"ecosystem":"Vendor product","name":"http-proxy-middleware","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"chimurai\",\n                    \"product\": \"http-proxy-middleware\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 3.0.4, < 3.0.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 4.0.0, < 4.1.1\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N","score":7.5,"severity":"HIGH"}],"references":["https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-55603","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-55603","identifiers":["CVE-2026-55603"]},"retained":false,"historicalAffected":[]}],"coverage":[]}