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CVE-2026-84695

Estado: AplazadaCrítica (9.3)—

BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers.

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad de XSS almacenado (CWE-79) en endpoint de upload de dibujos que acepta SVG sin validación, ejecutándose en navegadores de administradores. Requiere UI:P (interacción del usuario al acceder la galería) y permisos de editor, pero el XSS es la explotación clave.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

User TrainingRestrict Web-Based ContentApplication Developer GuidanceActive Directory ConfigurationUser Account ManagementPrivileged Account Management

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Bookstackapp — BookstackAI

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-84695",
  "cveTags": [],
  "metrics": {
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-84695",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-02T13:42:25.853414Z"
        }
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    "cvssMetricV31": [
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        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 8.7,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
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      }
    ],
    "cvssMetricV40": [
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        "type": "Secondary",
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        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 9.3,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "PASSIVE",
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          "subIntegrityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
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          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
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          "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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  },
  "affected": [
    {
      "source": "disclosure@vulncheck.com",
      "affectedData": [
        {
          "repo": "https://github.com/BookStackApp/BookStack",
          "vendor": "bookstackapp",
          "product": "bookstack",
          "versions": [
            {
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              "version": "0",
              "lessThan": "26.05.4",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
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              "versionType": "custom"
            }
          ],
          "packageURL": "pkg:github/BookStackApp/BookStack",
          "collectionURL": "https://github.com/BookStackApp/BookStack",
          "defaultStatus": "unaffected"
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  ],
  "published": "2026-09-02T01:17:24.400",
  "references": [
    {
      "url": "https://github.com/BookStackApp/BookStack",
      "source": "disclosure@vulncheck.com"
    },
    {
      "url": "https://github.com/BookStackApp/BookStack/blob/v26.05.3/app/Uploads/ImageService.php",
      "source": "disclosure@vulncheck.com"
    },
    {
      "url": "https://github.com/BookStackApp/BookStack/commit/ac0348a79f3ddd004ca87703948cb9c7d19a420a",
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    {
      "url": "https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4",
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      "url": "https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/",
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      "url": "https://www.vulncheck.com/advisories/bookstack-before-26.05.4-stored-xss-via-drawing-upload",
      "source": "disclosure@vulncheck.com"
    }
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  "weaknesses": [
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      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers."
    }
  ],
  "lastModified": "2026-09-08T20:18:59.270",
  "sourceIdentifier": "disclosure@vulncheck.com"
}