{
  "entry": {
    "kind": "vuln",
    "slug": "cve-2026-21520",
    "name": "CVE-2026-21520",
    "vendor": "Copilot Studio",
    "description": "Copilot Studio concatenated SharePoint form input directly into the agent's system prompt with no sanitization, allowing an attacker filling a public comment field to inject a fake system-role message that overrode agent instructions and directed it to exfiltrate SharePoint customer data via Outlook. Discovered by Capsule Security; Microsoft patched January 15, 2026, though data had already been exfiltrated during the disclosure window.",
    "website": "https://nvd.nist.gov/vuln/detail/CVE-2026-21520",
    "repository": null,
    "documentationUrl": null,
    "license": null,
    "version": null,
    "trustLevel": "advisory",
    "capabilities": [],
    "packaging": null,
    "configFiles": null,
    "category": "agent",
    "updatedAt": "2026-01-17",
    "risk": {
      "score": 75,
      "band": "high",
      "signals": [],
      "dangerousCombos": []
    },
    "dangerousCombos": [],
    "vuln": {
      "id": "CVE-2026-21520",
      "aliases": [
        "ti-008"
      ],
      "title": "CVE-2026-21520: Microsoft Copilot Studio Indirect Prompt Injection (\"ShareLeak\")",
      "summary": "Copilot Studio concatenated SharePoint form input directly into the agent's system prompt with no sanitization, allowing an attacker filling a public comment field to inject a fake system-role message that overrode agent instructions and directed it to exfiltrate SharePoint customer data via Outlook. Discovered by Capsule Security; Microsoft patched January 15, 2026, though data had already been exfiltrated during the disclosure window.",
      "severity": "high",
      "cvss": {
        "score": null,
        "vector": null,
        "version": null
      },
      "cwe": [],
      "attackType": [
        "Prompt injection",
        "Data exfiltration"
      ],
      "componentType": "agent",
      "component": {
        "name": "Copilot Studio",
        "vendor": null,
        "package": null,
        "ecosystem": null,
        "catalogSlug": null
      },
      "affected": [
        {
          "range": "Copilot Studio (pre-Jan 15 2026 patch)",
          "fixed": null
        }
      ],
      "exploited": false,
      "exploitPublic": false,
      "publishedAt": "2026-01-17",
      "modifiedAt": "2026-01-17",
      "lastVerified": "2026-11-01",
      "references": [
        {
          "type": "cve",
          "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-21520"
        }
      ],
      "mitigation": "Apply Microsoft January 2026 security update. Audit SharePoint forms for injected content. Review Copilot Studio agent configurations for missing input sanitization.",
      "detectedByAnomity": true
    }
  }
}