{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:chimurai:http-proxy-middleware:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "3.0.4"
              },
              {
                "fixed": "3.0.7"
              },
              {
                "introduced": "4.0.0"
              },
              {
                "fixed": "4.1.1"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "01934d33b157b2d49f7099a18ceec165e7502040"
            },
            {
              "fixed": "8cc4eba839e6cd95ebc073b2b48c4124ed72c302"
            },
            {
              "introduced": "8f356bcb5fce079460564f729da55814363361a6"
            },
            {
              "fixed": "b3b98d2846aa6a0cc9a1a08b8b152a634bb4741e"
            }
          ],
          "repo": "https://github.com/chimurai/http-proxy-middleware",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-gcq2-9pq2-cxqm"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-93"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55603.json"
  },
  "details": "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.",
  "id": "CVE-2026-55603",
  "modified": "2026-07-08T05:37:50.967267299Z",
  "published": "2026-06-22T20:07:05.034Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55603.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55603"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`"
}