{
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    "csaf_version": "2.0",
    "distribution": {
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      "tlp": {
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      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      },
      {
        "category": "general",
        "text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
        "title": "Customer Action"
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        "summary": "CVE-2026-40421 Microsoft Word Information Disclosure Vulnerability - HTML",
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        "summary": "Microsoft Exploitability Index",
        "url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
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      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
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    "title": "Microsoft Word Information Disclosure Vulnerability",
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      "revision_history": [
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          "date": "2026-05-12T07:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
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        "name": "External Control of File Name or Path"
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        {
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          "text": "Microsoft",
          "title": "Assigning CNA"
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          "text": "An attacker must send a user a malicious Office file and convince them to open it.",
          "title": "According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?"
        },
        {
          "category": "faq",
          "text": "Exploiting this vulnerability could allow the disclosure of NTLM hashes.",
          "title": "What type of information could be disclosed by this vulnerability?"
        },
        {
          "category": "faq",
          "text": "An attacker who successfully exploited the vulnerability could view some sensitive information (Confidentiality) but not all resources within the impacted component may be divulged to the attacker. The attacker cannot make changes to disclosed information (Integrity) or limit access to the resource (Availability).",
          "title": "According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L),but lead to no loss of availability (A:N) and integrity (I:N)? What does that mean for this vulnerability?"
        },
        {
          "category": "faq",
          "text": "No, the Preview Pane is not an attack vector.",
          "title": "Is the Preview Pane an attack vector for this vulnerability?"
        }
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          "4",
          "5",
          "6",
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          "10"
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          "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40421"
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          "summary": "CVE-2026-40421 Microsoft Word Information Disclosure Vulnerability - CSAF",
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          "date": "2026-05-12T07:00:00.000Z",
          "details": "https://aka.ms/OfficeSecurityReleases:Security Update:https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates",
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            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "environmentalsScore": 0.0,
            "exploitCodeMaturity": "UNPROVEN",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "UNCHANGED",
            "temporalScore": 3.8,
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C",
            "version": "3.1"
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      ],
      "threats": [
        {
          "category": "impact",
          "details": "Information Disclosure"
        },
        {
          "category": "exploit_status",
          "details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely"
        }
      ],
      "title": "Microsoft Word Information Disclosure Vulnerability"
    }
  ]
}