CVE-2026-66370

Estado: ModificadaMedia (4.8)—

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.

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No script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id.

This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Puntuación base: 4.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.40%
Percentil entre todas las CVEs puntuadas: 32
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Rrrene — Htmlsanitizeex

CWE

CWE-601

Referencias

JSON original (NVD)

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          "vendor": "rrrene",
          "modules": [
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          ],
          "packageURL": "pkg:hex/html_sanitize_ex",
          "packageName": "html_sanitize_ex",
          "programFiles": [
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            "lib/html_sanitize_ex.ex"
          ],
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          "defaultStatus": "unaffected",
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          "vendor": "rrrene",
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          "packageURL": "pkg:github/rrrene/html_sanitize_ex",
          "packageName": "rrrene/html_sanitize_ex",
          "programFiles": [
            "lib/html_sanitize_ex/scrubber/html5.ex",
            "lib/html_sanitize_ex.ex"
          ],
          "collectionURL": "https://github.com",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"
            },
            {
              "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"
            },
            {
              "name": "'Elixir.HtmlSanitizeEx':html5/1"
            }
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        }
      ]
    }
  ],
  "published": "2026-08-06T16:16:48.420",
  "references": [
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      "tags": [
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        "Third Party Advisory"
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        "Third Party Advisory"
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      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
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  "vulnStatus": "Modified",
  "weaknesses": [
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      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "description": [
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          "lang": "en",
          "value": "CWE-601"
        }
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    }
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  "descriptions": [
    {
      "lang": "en",
      "value": "URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.\n\nNo script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3."
    }
  ],
  "lastModified": "2026-08-19T12:18:34.240",
  "configurations": [
    {
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        {
          "negate": false,
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              "versionEndExcluding": "1.5.3",
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          ],
          "operator": "OR"
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  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}