CVE-2026-66843

Estado: ModificadaBaja (2.3)—

Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase "javascript:", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive.

This is not unconditional cross-site scripting. A javascript: URL does not execute through <object data> in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path.

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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:P/VC:N/VI:N/VA:N/SC:L/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: 2.3

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.51%
Percentil entre todas las CVEs puntuadas: 42
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-829

Referencias

JSON original (NVD)

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  "id": "CVE-2026-66843",
  "cveTags": [],
  "metrics": {
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          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-08-06T15:40:41.682905Z"
        }
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        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
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          "version": "3.1",
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          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "integrityImpact": "LOW",
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        "type": "Secondary",
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        "cvssData": {
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          "Automatable": "NOT_DEFINED",
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          "baseSeverity": "LOW",
          "valueDensity": "NOT_DEFINED",
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          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "PASSIVE",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "LOW",
          "vulnIntegrityImpact": "NONE",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
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      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/rrrene/html_sanitize_ex",
          "vendor": "rrrene",
          "modules": [
            "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
            "Elixir.HtmlSanitizeEx"
          ],
          "product": "html_sanitize_ex",
          "versions": [
            {
              "status": "affected",
              "version": "0.3.1",
              "lessThan": "1.4.5",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "1.5.0-rc.0",
              "lessThan": "1.5.3",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:hex/html_sanitize_ex",
          "packageName": "html_sanitize_ex",
          "programFiles": [
            "lib/html_sanitize_ex/scrubber/html5.ex",
            "lib/html_sanitize_ex.ex"
          ],
          "collectionURL": "https://repo.hex.pm",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"
            },
            {
              "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"
            },
            {
              "name": "'Elixir.HtmlSanitizeEx':html5/1"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/rrrene/html_sanitize_ex",
          "vendor": "rrrene",
          "modules": [
            "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
            "Elixir.HtmlSanitizeEx"
          ],
          "product": "html_sanitize_ex",
          "versions": [
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              "changes": [
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              ],
              "version": "8976d64ea0b77d26093a94a43ec48a3978e8d028",
              "lessThan": "*",
              "versionType": "git"
            }
          ],
          "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"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-08-06T16:16:49.627",
  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-66843.html",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf",
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      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/rrrene/html_sanitize_ex/commit/ce038aa1af5a960d50f8eb5d368cc57bb2b9a9f0",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj",
      "tags": [
        "Broken Link"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66843",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "description": [
        {
          "lang": "en",
          "value": "CWE-829"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase \"javascript:\", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive.\n\nThis is not unconditional cross-site scripting. A javascript: URL does not execute through <object data> in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path.\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": "2026-08-19T12:18:34.807",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "DE85053C-AE84-4570-A90C-4D4CCD7A4BA3",
              "versionEndExcluding": "1.5.3",
              "versionStartIncluding": "0.3.1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}