FKIE_CVE-2026-21509

Vulnerability from fkie_nvd - Published: 2026-01-26 18:16 - Updated: 2026-01-27 16:19
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
References
secure@microsoft.comhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509US Government Resource
Impacted products
Vendor Product Version
microsoft 365_apps -
microsoft 365_apps -
microsoft office 2016
microsoft office 2016
microsoft office 2019
microsoft office 2019
microsoft office_long_term_servicing_channel 2021
microsoft office_long_term_servicing_channel 2021
microsoft office_long_term_servicing_channel 2024
microsoft office_long_term_servicing_channel 2024
To clipboard 

{
  "cisaActionDue": "2026-02-16",
  "cisaExploitAdd": "2026-01-26",
  "cisaRequiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.",
  "cisaVulnerabilityName": "Microsoft Office Security Feature Bypass Vulnerability",
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*",
              "matchCriteriaId": "3259EBFE-AE2D-48B8-BE9A-E22BBDB31378",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*",
              "matchCriteriaId": "CD25F492-9272-4836-832C-8439EBE64CCF",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x64:*",
              "matchCriteriaId": "72324216-4EB3-4243-A007-FEF3133C7DF9",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x86:*",
              "matchCriteriaId": "0FBB0E61-7997-4F26-9C07-54912D3F1C10",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*",
              "matchCriteriaId": "CF5DDD09-902E-4881-98D0-CB896333B4AA",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*",
              "matchCriteriaId": "26A3B226-5D7C-4556-9350-5222DC8EFC2C",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*",
              "matchCriteriaId": "851BAC4E-9965-4F40-9A6C-B73D9004F4C1",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*",
              "matchCriteriaId": "23B2FA23-76F4-4D83-A718-B8D04D7EA37B",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*",
              "matchCriteriaId": "D31E509A-0B2E-4B41-88C4-0099E800AFE6",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*",
              "matchCriteriaId": "017A7041-BEF1-4E4E-AC8A-EFC6AFEB01FE",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally."
    }
  ],
  "id": "CVE-2026-21509",
  "lastModified": "2026-01-27T16:19:42.330",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "secure@microsoft.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-01-26T18:16:38.540",
  "references": [
    {
      "source": "secure@microsoft.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "US Government Resource"
      ],
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509"
    }
  ],
  "sourceIdentifier": "secure@microsoft.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-807"
        }
      ],
      "source": "secure@microsoft.com",
      "type": "Secondary"
    }
  ]
}


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Detection rules are retrieved from Rulezet.