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CVE-2026-1721

Estado: AplazadaMedia (6.2)—

Summary

A Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The `error_description` query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.

Root cause

The OAuth callback handler in `site/ai-playground/src/server.ts` directly interpolated the `authError` value, sourced from the `error_description` query parameter, into an inline `<script>` tag.

Impact

An attacker could craft a malicious link that, when clicked by a victim, would:

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Mitigation:

Detalles técnicos trazas, registros y código del informe original
  *  Steal user chat message history - Access all LLM interactions stored in the user's session.

  *  Access connected MCP Servers - Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf

  *  PR:  https://github.com/cloudflare/agents/pull/841 https://github.com/cloudflare/agents/pull/841

  *  Agents-sdk users should upgrade to agents@0.3.10

  *  Developers using configureOAuthCallback with custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.

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)

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

Cloudflare — AgentsAI

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-1721",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-1721",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-02-13T13:10:24.218273Z"
        }
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "cna@cloudflare.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 6.2,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "ACTIVE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "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": "HIGH",
          "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"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "cna@cloudflare.com",
      "affectedData": [
        {
          "repo": "https://github.com/cloudflare/agents",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "0.3.10",
              "versionType": "git"
            }
          ],
          "packageName": "agents",
          "collectionURL": "https://github.com/cloudflare",
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-02-13T03:15:52.467",
  "references": [
    {
      "url": "https://github.com/cloudflare/agents/pull/841",
      "source": "cna@cloudflare.com"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Summary\n\nA Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The `error_description` query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.\n\n\n\n\nRoot cause\n\nThe OAuth callback handler in `site/ai-playground/src/server.ts` directly interpolated the `authError` value, sourced from the `error_description` query parameter,  into an inline `<script>` tag.\n\n\nImpact\n\nAn attacker could craft a malicious link that, when clicked by a victim, would:\n\n  *  Steal user chat message history - Access all LLM interactions stored in the user's session.\n\n\n  *  Access connected MCP Servers - Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf\n\n\n\n\n\nMitigation:\n\n  *  PR:  https://github.com/cloudflare/agents/pull/841 https://github.com/cloudflare/agents/pull/841 \n\n\n\n\n  *  Agents-sdk users should upgrade to agents@0.3.10\n\n\n\n\n  *  Developers using configureOAuthCallback with custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation."
    },
    {
      "lang": "es",
      "value": "Resumen\n\nUna vulnerabilidad de Cross-Site Scripting Reflejado (XSS) fue descubierta en el manejador de callback de OAuth del AI Playground. El parámetro de consulta `error_description` fue directamente interpolado en una etiqueta de script HTML sin el escape adecuado, permitiendo a los atacantes ejecutar JavaScript arbitrario en el contexto de la sesión de la víctima.\n\nCausa raíz\n\nEl manejador de callback de OAuth en `site/ai-playground/src/server.ts` interpoló directamente el valor `authError`, obtenido del parámetro de consulta `error_description`, en una etiqueta `"
    }
  ],
  "lastModified": "2026-06-17T10:16:23.767",
  "sourceIdentifier": "cna@cloudflare.com"
}