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CVE-2026-54889

Full vulnerability record from the local CVENow database.

Description

Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in leandrocp mdex allows cross-site scripting via unsanitized URL schemes in Quill Delta output. 'Elixir.MDEx':to_delta/2 converts Markdown into a Quill Delta. 'Elixir.MDEx.DeltaConverter':default_convert_node/3 in lib/mdex/delta_converter.ex copies the URL of a link, wikilink, or image node directly from the parsed Markdown into the Delta "link" or "image" attribute without applying a scheme allowlist or any normalization. An attacker who controls the Markdown text can supply a javascript: URL (for example [click](javascript:alert(document.cookie))) that survives verbatim into the Delta attribute. When the Delta is rendered to HTML by a downstream renderer (such as quill-delta-to-html or the Quill client), the attribute becomes an <a href> or <img src>, and the javascript: scheme executes in the browser of anyone who views the rendered content. The link and wikilink cases are the strongest vectors because javascript: in an href executes on click; the image case is lower impact because javascript: in <img src> generally does not execute in modern browsers. This issue affects mdex: from 0.8.3 before 0.13.2.

Severity
MEDIUM
CVSS score
5.1 (v4.0)
Vulnerability status
Deferred
Source identifier
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Published
2026-06-29 20:17:39.407000
Last modified
2026-10-25 21:10:00.770000
View original CVE JSON 
{
  "id": "CVE-2026-54889",
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "published": "2026-06-29T20:17:39.407",
  "lastModified": "2026-10-25T21:10:00.770",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in leandrocp mdex allows cross-site scripting via unsanitized URL schemes in Quill Delta output.\n\n'Elixir.MDEx':to_delta/2 converts Markdown into a Quill Delta. 'Elixir.MDEx.DeltaConverter':default_convert_node/3 in lib/mdex/delta_converter.ex copies the URL of a link, wikilink, or image node directly from the parsed Markdown into the Delta \"link\" or \"image\" attribute without applying a scheme allowlist or any normalization.\n\nAn attacker who controls the Markdown text can supply a javascript: URL (for example [click](javascript:alert(document.cookie))) that survives verbatim into the Delta attribute. When the Delta is rendered to HTML by a downstream renderer (such as quill-delta-to-html or the Quill client), the attribute becomes an <a href> or <img src>, and the javascript: scheme executes in the browser of anyone who views the rendered content. The link and wikilink cases are the strongest vectors because javascript: in an href executes on click; the image case is lower impact because javascript: in <img src> generally does not execute in modern browsers.\n\nThis issue affects mdex: from 0.8.3 before 0.13.2."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de Neutralización Incorrecta de Entrada Durante la Generación de Páginas Web (XSS) en leandrocp mdex permite cross-site scripting a través de esquemas de URL no saneados en la salida de Quill Delta.\n\n’Elixir.MDEx’:to_delta/2 convierte Markdown en un Quill Delta. ’Elixir.MDEx.DeltaConverter’:default_convert_node/3 en lib/mdex/delta_converter.ex copia la URL de un enlace, wikienlace o nodo de imagen directamente desde el Markdown analizado en el atributo Delta “link” o “image” sin aplicar una lista blanca de esquemas o ninguna normalización.\n\nUn atacante que controla el texto Markdown puede proporcionar una URL javascript_disabled: (por ejemplo [click](javascript_disabled: alert(document.cookie))) que sobrevive textualmente en el atributo Delta. Cuando el Delta se renderiza a HTML por un renderizador descendente (como quill-delta-to-html o el cliente Quill), el atributo se convierte en un <a href> o <img src>, y el esquema javascript_disabled: se ejecuta en el navegador de cualquiera que vea el contenido renderizado. Los casos de enlace y wikienlace son los vectores más fuertes porque javascript_disabled: en un href se ejecuta al hacer clic; el caso de la imagen tiene un impacto menor porque javascript_disabled: en <img src> generalmente no se ejecuta en navegadores modernos.\n\nEste problema afecta a mdex: desde 0.8.3 antes de 0.13.2."
    }
  ],
  "affected": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "affectedData": [
        {
          "vendor": "leandrocp",
          "product": "mdex",
          "defaultStatus": "unaffected",
          "collectionURL": "https://repo.hex.pm",
          "packageName": "mdex",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
          ],
          "modules": [
            "'Elixir.MDEx'",
            "'Elixir.MDEx.DeltaConverter'"
          ],
          "programFiles": [
            "lib/mdex.ex",
            "lib/mdex/delta_converter.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.MDEx':to_delta/2"
            },
            {
              "name": "'Elixir.MDEx.DeltaConverter':convert/2"
            },
            {
              "name": "'Elixir.MDEx.DeltaConverter':default_convert_node/3"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex",
          "packageURL": "pkg:hex/mdex",
          "versions": [
            {
              "version": "0.8.3",
              "lessThan": "0.13.2",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "leandrocp",
          "product": "mdex",
          "defaultStatus": "unaffected",
          "collectionURL": "https://github.com",
          "packageName": "leandrocp/mdex",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
          ],
          "modules": [
            "'Elixir.MDEx'",
            "'Elixir.MDEx.DeltaConverter'"
          ],
          "programFiles": [
            "lib/mdex.ex",
            "lib/mdex/delta_converter.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.MDEx':to_delta/2"
            },
            {
              "name": "'Elixir.MDEx.DeltaConverter':convert/2"
            },
            {
              "name": "'Elixir.MDEx.DeltaConverter':default_convert_node/3"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex",
          "packageURL": "pkg:github/leandrocp/mdex",
          "versions": [
            {
              "version": "9852db2456fdc9d856eb636603a7f608e22e3793",
              "lessThan": "2817147f5b87ce7186aa604c9ee72499485b8f2f",
              "versionType": "git",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/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",
          "baseScore": 5.1,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "userInteraction": "ACTIVE",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "LOW",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-06-29T20:48:34.044130Z",
          "id": "CVE-2026-54889",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-54889.html",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/leandrocp/mdex/commit/2817147f5b87ce7186aa604c9ee72499485b8f2f",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/leandrocp/mdex/security/advisories/GHSA-4383-7xfp-gpph",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-54889",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/leandrocp/mdex/security/advisories/GHSA-4383-7xfp-gpph",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ]
}