CVE-2026-55603

{
  "id": "CVE-2026-55603",
  "sourceIdentifier": "[email protected]",
  "published": "2026-06-22T21:16:26.033",
  "lastModified": "2026-10-25T23:10:00.167",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "http-proxy-middleware es middleware de http-proxy de node.js. Desde 3.0.4 hasta 3.0.7 y 4.1.1, fixRequestBody() es el ayudante documentado de la biblioteca para reemitir un cuerpo de solicitud que ya fue consumido por un analizador de cuerpo. Cuando el Content-Type saliente es multipart/form-data, reconstruye el cuerpo con handlerFormDataBodyData(), que interpola cada clave y valor de req.body directamente en el formato de cable multipart sin neutralizar CR/LF. Un \\r\\n dentro de un valor (o clave) permite a un atacante cerrar la parte actual e inyectar una parte de formulario completamente nueva. Debido a que el propio analizador de cuerpo del proxy vio un único valor opaco, cualquier política o validación del lado de la pasarela realizada en req.body se evalúa contra un conjunto diferente de campos que los que el backend ascendente finalmente analiza, una desincronización de solicitud/parámetro a través del límite de confianza. Esta vulnerabilidad está corregida en 3.0.7 y 4.1.1."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "chimurai",
          "product": "http-proxy-middleware",
          "versions": [
            {
              "version": ">= 3.0.4, < 3.0.7",
              "status": "affected"
            },
            {
              "version": ">= 4.0.0, < 4.1.1",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "CHANGED",
          "confidentialityImpact": "LOW",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 4.7
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-06-23T12:20:45.426994Z",
          "id": "CVE-2026-55603",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-93"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:chimurai:http-proxy-middleware:*:*:*:*:*:*:*:*",
              "versionStartIncluding": "3.0.4",
              "versionEndExcluding": "3.0.7",
              "matchCriteriaId": "8281B19B-A543-4996-B6E0-3A43AD44585B"
            },
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:chimurai:http-proxy-middleware:*:*:*:*:*:*:*:*",
              "versionStartIncluding": "4.0.0",
              "versionEndExcluding": "4.1.1",
              "matchCriteriaId": "D9D194C5-E95E-410C-BFB4-A36DCC12F656"
            }
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  ],
  "references": [
    {
      "url": "https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    }
  ]
}