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CVE-2026-33500

Estado: AnalizadaMedia (5.4)—

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the fix for CVE-2026-27568 (GHSA-rcqw-6466-3mv7) introduced a custom `ParsedownSafeWithLinks` class that sanitizes raw HTML `<a>` and `<img>` tags in comments, but explicitly disables Parsedown's `safeMode`. This creates a bypass: markdown link syntax `[text](javascript:alert(1))` is processed by Parsedown's `inlineLink()` method, which does not go through the custom `sanitizeATag()` sanitization (that only handles raw HTML tags).

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With `safeMode` disabled, Parsedown's built-in `javascript:` URI filtering (`sanitiseElement()`/`filterUnsafeUrlInAttribute()`) is also inactive. An attacker can inject stored XSS via comment markdown links. Commit 3ae02fa240939dbefc5949d64f05790fd25d728d contains a patch.

CVSS

Probabilidad de explotación (EPSS)

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)

Wwbn — Avideo

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-33500",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-33500",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-03-24T17:38:19.380717Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 5.4,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 2.7,
        "exploitabilityScore": 2.3
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "WWBN",
          "product": "AVideo",
          "versions": [
            {
              "status": "affected",
              "version": "<= 26.0"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-03-23T17:16:51.340",
  "references": [
    {
      "url": "https://github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d",
      "tags": [
        "Patch"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "WWBN AVideo is an open source video platform. In versions up to and including 26.0, the fix for CVE-2026-27568 (GHSA-rcqw-6466-3mv7) introduced a custom `ParsedownSafeWithLinks` class that sanitizes raw HTML `<a>` and `<img>` tags in comments, but explicitly disables Parsedown's `safeMode`. This creates a bypass: markdown link syntax `[text](javascript:alert(1))` is processed by Parsedown's `inlineLink()` method, which does not go through the custom `sanitizeATag()` sanitization (that only handles raw HTML tags). With `safeMode` disabled, Parsedown's built-in `javascript:` URI filtering (`sanitiseElement()`/`filterUnsafeUrlInAttribute()`) is also inactive. An attacker can inject stored XSS via comment markdown links. Commit 3ae02fa240939dbefc5949d64f05790fd25d728d contains a patch."
    },
    {
      "lang": "es",
      "value": "WWBN AVideo es una plataforma de video de código abierto. En versiones hasta la 26.0 inclusive, la corrección para CVE-2026-27568 (GHSA-rcqw-6466-3mv7) introdujo una clase personalizada ParsedownSafeWithLinks que sanitiza las etiquetas HTML sin procesar `<a rel=\"nofollow\">` e `` en los comentarios, pero deshabilita explícitamente el safeMode de Parsedown. Esto crea un bypass: la sintaxis de enlace markdown `[text](javascript:alert(1))` es procesada por el método inlineLink() de Parsedown, que no pasa por la sanitización personalizada sanitizeATag() (que solo maneja etiquetas HTML sin procesar). Con safeMode deshabilitado, el filtrado de URI `javascript:` incorporado de Parsedown (sanitiseElement()/filterUnsafeUrlInAttribute()) también está inactivo. Un atacante puede inyectar XSS almacenado a través de enlaces markdown en comentarios. El commit 3ae02fa240939dbefc5949d64f05790fd25d728d contiene un parche.</a>"
    }
  ],
  "lastModified": "2026-06-17T10:37:36.503",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:wwbn:avideo:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "774C24F1-9D26-484F-B931-1DA107C8F588",
              "versionEndIncluding": "26.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security-advisories@github.com"
}