CVE-2026-48788

{
  "id": "CVE-2026-48788",
  "sourceIdentifier": "[email protected]",
  "published": "2026-06-17T13:20:43.490",
  "lastModified": "2026-10-25T23:10:00.167",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. Versions 1.6.0 through 1.15.0 contain a Cross-Site Scripting (XSS) vulnerability exploitable through content-type spoofing. The Remark42 image proxy fetches an arbitrary remote URL and re-serves the response from Remark42's own origin. During the download phase, the proxy determines whether the resource is an image by inspecting only the Content-Type header advertised by the remote server, never examining the actual bytes; during the serving phase, it instead derives the response Content-Type by sniffing those bytes with http.DetectContentType. An attacker can exploit this inconsistency by hosting a URL that advertises Content-Type: image/png while returning an HTML/JavaScript body: the download check accepts it as an image, the serving path sniffs the body and emits Content-Type: text/html, and the browser renders the attacker-controlled HTML/JavaScript as a document within Remark42's origin. Exploitation requires no Remark42 account on the target instance; the attacker only needs to host the malicious upstream URL and deliver the proxy link to a victim by any means, such as email, direct message, or a link on another website. This issue has been fixed in version 1.16.0."
    },
    {
      "lang": "es",
      "value": "Remark42 es un motor de comentarios autoalojado para blogs, artículos o cualquier otro lugar donde los lectores puedan añadir comentarios. Las versiones 1.6.0 a la 1.15.0 contienen una vulnerabilidad de Cross-Site Scripting (XSS) explotable a través de la suplantación de tipo de contenido. El proxy de imágenes de Remark42 obtiene una URL remota arbitraria y vuelve a servir la respuesta desde el propio origen de Remark42. Durante la fase de descarga, el proxy determina si el recurso es una imagen inspeccionando solo el encabezado Content-Type anunciado por el servidor remoto, sin examinar nunca los bytes reales; durante la fase de servicio, en su lugar, deriva el Content-Type de la respuesta detectando esos bytes con http.DetectContentType. Un atacante puede explotar esta inconsistencia alojando una URL que anuncia Content-Type: image/png mientras devuelve un cuerpo HTML/javascript_disabled: la verificación de descarga lo acepta como una imagen, la ruta de servicio detecta el cuerpo y emite Content-Type: text/html, y el navegador renderiza el HTML/JavaScript controlado por el atacante como un documento dentro del origen de Remark42. La explotación no requiere una cuenta de Remark42 en la instancia objetivo; el atacante solo necesita alojar la URL maliciosa de origen y entregar el enlace del proxy a una víctima por cualquier medio, como correo electrónico, mensaje directo o un enlace en otro sitio web. Este problema ha sido solucionado en la versión 1.16.0."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "umputun",
          "product": "remark42",
          "versions": [
            {
              "version": ">= 1.6.0, < 1.16.0",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV30": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.0",
          "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "CHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "LOW",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.7
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-06-17T13:19:50.596883Z",
          "id": "CVE-2026-48788",
          "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-79"
        },
        {
          "lang": "en",
          "value": "CWE-436"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/umputun/remark42/commit/78d6de6bce1e961f023969da3ec8a00dd80c9ae8",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/umputun/remark42/releases/tag/v1.16.0",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/umputun/remark42/security/advisories/GHSA-4c8j-mgm4-qqvp",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/umputun/remark42/security/advisories/GHSA-4c8j-mgm4-qqvp",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ]
}