Vulnerability-Lookup

BDU:2026-00828 (CVE-2026-21509)

Vulnerability from fstec – Published: 2026-01-27 – Updated: 2026-01-28 – View on bdu.fstec.ru Exploit exists Yes Fixed

Title

Уязвимость пакета программ Microsoft Office, связанная с использованием ненадежных входных данных при принятии решений по безопасности, позволяющая нарушителю обойти существующие механизмы безопасности

Summary

Уязвимость пакета программ Microsoft Office связана с использованием ненадежных входных данных при принятии решений по безопасности. Эксплуатация уязвимости может позволить нарушителю обойти существующие механизмы безопасности

Severity

7.2 (High) CVSS 2.0


                      
                        AV:L/AC:L/Au:N/C:C/I:C/A:C

7.8 (High) CVSS 3.1


                      
                        CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Class

Code vulnerability

Status

Confirmed by the vendor

Exploitation

Spoofing

Incidents

Yes

Remediation

Software update

CWE

CWE-807 - Зависимость от ненадежных входных данных при принятии решения по безопасности

Aliases

CVE-2026-21509

References

3 references

URL
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509
https://thehackernews.com/2026/01/microsoft-issues-emergency-patch-for.html

Impacted products

5 products from 1 vendor

Vendors

Microsoft Corp

Products

Microsoft 365 Apps for Enterprise, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office 2016, Microsoft Office 2019

Versions

- (Microsoft 365 Apps for Enterprise), - (Microsoft Office LTSC 2021), - (Microsoft Office LTSC 2024), до 16.0.5539.1001 (Microsoft Office 2016), до 16.0.10417.20095 (Microsoft Office 2019)

Product types

Application software

Mitigations

Установка обновлений из доверенных источников. В связи со сложившейся обстановкой и введенными санкциями против Российской Федерации рекомендуется устанавливать обновления программного обеспечения только после оценки всех сопутствующих рисков. Компенсирующие меры: - использование SIEM-систем для отслеживания попыток эксплуатации уязвимости. - изменение ключей реестра следующим образом: 1) создание резервной копии реестра; 2) завершение процессов, связанных с работой приложений Microsoft Office; 3) поиск одного из следующих подразделов реестра: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\16.0\Common\COM Compatibility\ (для 64-разрядной версии MSI Office или 32-разрядной версии MSI Office на 32-разрядной Windows) или HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\16.0\Common\COM Compatibility\ (для 32-разрядного MSI Office на 64-разрядной Windows) или HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\REGISTRY\MACHINE\Software\Microsoft\Office\16.0\Common\COM Compatibility\ (для 64-разрядной версии Click2Run Office или 32-разрядной версии Click2Run Office на 32-разрядной Windows) или HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\REGISTRY\MACHINE\Software\WOW6432Node\Microsoft\Office\16.0\Common\COM Compatibility\ (для 32-разрядной версии Click2Run Office на 64-разрядной Windows); 4) в случае отсутствия подраздела, его добавление с именем {EAB22AC3-30C1-11CF-A7EB-0000C05BAE0B}, выбрав в контекстном меню пункты «Совместимость COM» и «Добавить ключ»; 5) включение в реестр нового шестнадцатеричного ключа с именем Compatibility Flags типа REG_DWORD и значением 400; 6) запуск приложений Microsoft Office. Использование рекомендаций: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509

Remediation

TO2457 Обновление для системы безопасности Microsoft Office 2016 для x64 систем (KB5002713), TO2458 Обновление для системы безопасности Microsoft Office 2016 для x32 систем (KB5002713)

JSON

To clipboard

{
  "CVSS 2.0": "AV:L/AC:L/Au:N/C:C/I:C/A:C",
  "CVSS 3.0": "AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "TO2457, TO2458",
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": "TO2457 \u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u0434\u043b\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u044b \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 Microsoft Office 2016 \u0434\u043b\u044f x64 \u0441\u0438\u0441\u0442\u0435\u043c (KB5002713), TO2458 \u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u0434\u043b\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u044b \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 Microsoft Office 2016 \u0434\u043b\u044f x32 \u0441\u0438\u0441\u0442\u0435\u043c (KB5002713)",
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "Microsoft Corp",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "- (Microsoft 365 Apps for Enterprise), - (Microsoft Office LTSC 2021), - (Microsoft Office LTSC 2024), \u0434\u043e 16.0.5539.1001 (Microsoft Office 2016), \u0434\u043e 16.0.10417.20095 (Microsoft Office 2019)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0423\u0441\u0442\u0430\u043d\u043e\u0432\u043a\u0430 \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0439 \u0438\u0437 \u0434\u043e\u0432\u0435\u0440\u0435\u043d\u043d\u044b\u0445 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u043e\u0432. \u0412 \u0441\u0432\u044f\u0437\u0438 \u0441\u043e \u0441\u043b\u043e\u0436\u0438\u0432\u0448\u0435\u0439\u0441\u044f \u043e\u0431\u0441\u0442\u0430\u043d\u043e\u0432\u043a\u043e\u0439 \u0438 \u0432\u0432\u0435\u0434\u0435\u043d\u043d\u044b\u043c\u0438 \u0441\u0430\u043d\u043a\u0446\u0438\u044f\u043c\u0438 \u043f\u0440\u043e\u0442\u0438\u0432 \u0420\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u043e\u0439 \u0424\u0435\u0434\u0435\u0440\u0430\u0446\u0438\u0438 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0443\u0435\u0442\u0441\u044f \u0443\u0441\u0442\u0430\u043d\u0430\u0432\u043b\u0438\u0432\u0430\u0442\u044c \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f \u0442\u043e\u043b\u044c\u043a\u043e \u043f\u043e\u0441\u043b\u0435 \u043e\u0446\u0435\u043d\u043a\u0438 \u0432\u0441\u0435\u0445 \u0441\u043e\u043f\u0443\u0442\u0441\u0442\u0432\u0443\u044e\u0449\u0438\u0445 \u0440\u0438\u0441\u043a\u043e\u0432.\n\n\u041a\u043e\u043c\u043f\u0435\u043d\u0441\u0438\u0440\u0443\u044e\u0449\u0438\u0435 \u043c\u0435\u0440\u044b:\n- \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 SIEM-\u0441\u0438\u0441\u0442\u0435\u043c \u0434\u043b\u044f \u043e\u0442\u0441\u043b\u0435\u0436\u0438\u0432\u0430\u043d\u0438\u044f \u043f\u043e\u043f\u044b\u0442\u043e\u043a \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438.\n- \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0435 \u043a\u043b\u044e\u0447\u0435\u0439 \u0440\u0435\u0435\u0441\u0442\u0440\u0430 \u0441\u043b\u0435\u0434\u0443\u044e\u0449\u0438\u043c \u043e\u0431\u0440\u0430\u0437\u043e\u043c:\n1) \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u0435 \u0440\u0435\u0437\u0435\u0440\u0432\u043d\u043e\u0439 \u043a\u043e\u043f\u0438\u0438 \u0440\u0435\u0435\u0441\u0442\u0440\u0430;\n2) \u0437\u0430\u0432\u0435\u0440\u0448\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u043e\u0432, \u0441\u0432\u044f\u0437\u0430\u043d\u043d\u044b\u0445 \u0441 \u0440\u0430\u0431\u043e\u0442\u043e\u0439 \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u0439 Microsoft Office;\n3) \u043f\u043e\u0438\u0441\u043a \u043e\u0434\u043d\u043e\u0433\u043e \u0438\u0437 \u0441\u043b\u0435\u0434\u0443\u044e\u0449\u0438\u0445 \u043f\u043e\u0434\u0440\u0430\u0437\u0434\u0435\u043b\u043e\u0432 \u0440\u0435\u0435\u0441\u0442\u0440\u0430:\nHKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Office\\16.0\\Common\\COM Compatibility\\ (\u0434\u043b\u044f 64-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 MSI Office \u0438\u043b\u0438 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 MSI Office \u043d\u0430 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 Windows)\n\n\u0438\u043b\u0438\n\nHKEY_LOCAL_MACHINE\\SOFTWARE\\WOW6432Node\\Microsoft\\Office\\16.0\\Common\\COM Compatibility\\ (\u0434\u043b\u044f 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0433\u043e MSI Office \u043d\u0430 64-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 Windows)\n\n\u0438\u043b\u0438\n\nHKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Office\\ClickToRun\\REGISTRY\\MACHINE\\Software\\Microsoft\\Office\\16.0\\Common\\COM Compatibility\\ (\u0434\u043b\u044f 64-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 Click2Run Office \u0438\u043b\u0438 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 Click2Run Office \u043d\u0430 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 Windows)\n\n\u0438\u043b\u0438\n\nHKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Office\\ClickToRun\\REGISTRY\\MACHINE\\Software\\WOW6432Node\\Microsoft\\Office\\16.0\\Common\\COM Compatibility\\ (\u0434\u043b\u044f 32-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 \u0432\u0435\u0440\u0441\u0438\u0438 Click2Run Office \u043d\u0430 64-\u0440\u0430\u0437\u0440\u044f\u0434\u043d\u043e\u0439 Windows);\n4) \u0432 \u0441\u043b\u0443\u0447\u0430\u0435 \u043e\u0442\u0441\u0443\u0442\u0441\u0442\u0432\u0438\u044f \u043f\u043e\u0434\u0440\u0430\u0437\u0434\u0435\u043b\u0430, \u0435\u0433\u043e \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u0441 \u0438\u043c\u0435\u043d\u0435\u043c {EAB22AC3-30C1-11CF-A7EB-0000C05BAE0B}, \u0432\u044b\u0431\u0440\u0430\u0432 \u0432 \u043a\u043e\u043d\u0442\u0435\u043a\u0441\u0442\u043d\u043e\u043c \u043c\u0435\u043d\u044e \u043f\u0443\u043d\u043a\u0442\u044b \u00ab\u0421\u043e\u0432\u043c\u0435\u0441\u0442\u0438\u043c\u043e\u0441\u0442\u044c COM\u00bb \u0438 \u00ab\u0414\u043e\u0431\u0430\u0432\u0438\u0442\u044c \u043a\u043b\u044e\u0447\u00bb;\n5) \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u0435 \u0432 \u0440\u0435\u0435\u0441\u0442\u0440 \u043d\u043e\u0432\u043e\u0433\u043e \u0448\u0435\u0441\u0442\u043d\u0430\u0434\u0446\u0430\u0442\u0435\u0440\u0438\u0447\u043d\u043e\u0433\u043e \u043a\u043b\u044e\u0447\u0430 \u0441 \u0438\u043c\u0435\u043d\u0435\u043c Compatibility Flags \u0442\u0438\u043f\u0430 REG_DWORD \u0438 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435\u043c 400;\n6) \u0437\u0430\u043f\u0443\u0441\u043a \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u0439 Microsoft Office.\n\n\n\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439:\nhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "26.01.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "28.01.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "27.01.2026",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2026-00828",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2026-21509",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "Microsoft 365 Apps for Enterprise, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office 2016, Microsoft Office 2019",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": null,
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043f\u0430\u043a\u0435\u0442\u0430 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c Microsoft Office, \u0441\u0432\u044f\u0437\u0430\u043d\u043d\u0430\u044f \u0441 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u043d\u0435\u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0445 \u0432\u0445\u043e\u0434\u043d\u044b\u0445 \u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u0440\u0438 \u043f\u0440\u0438\u043d\u044f\u0442\u0438\u0438 \u0440\u0435\u0448\u0435\u043d\u0438\u0439 \u043f\u043e \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u043e\u0431\u043e\u0439\u0442\u0438 \u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u044e\u0449\u0438\u0435 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u044b \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0421\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u0435\u0442",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u0417\u0430\u0432\u0438\u0441\u0438\u043c\u043e\u0441\u0442\u044c \u043e\u0442 \u043d\u0435\u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0445 \u0432\u0445\u043e\u0434\u043d\u044b\u0445 \u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u0440\u0438 \u043f\u0440\u0438\u043d\u044f\u0442\u0438\u0438 \u0440\u0435\u0448\u0435\u043d\u0438\u044f \u043f\u043e \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (CWE-807)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043f\u0430\u043a\u0435\u0442\u0430 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c Microsoft Office \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435\u043c \u043d\u0435\u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0445 \u0432\u0445\u043e\u0434\u043d\u044b\u0445 \u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u0440\u0438 \u043f\u0440\u0438\u043d\u044f\u0442\u0438\u0438 \u0440\u0435\u0448\u0435\u043d\u0438\u0439 \u043f\u043e \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u043e\u0431\u043e\u0439\u0442\u0438 \u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u044e\u0449\u0438\u0435 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u044b \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u041f\u043e\u0434\u043c\u0435\u043d\u0430 \u043f\u0440\u0438 \u0432\u0437\u0430\u0438\u043c\u043e\u0434\u0435\u0439\u0441\u0442\u0432\u0438\u0438",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509\nhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509\nhttps://thehackernews.com/2026/01/microsoft-issues-emergency-patch-for.html",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041f\u0440\u0438\u043a\u043b\u0430\u0434\u043d\u043e\u0435 \u041f\u041e \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-807",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0412\u044b\u0441\u043e\u043a\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 7,2)\n\u0412\u044b\u0441\u043e\u043a\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 7,8)"
}

CVE-2026-21509 (GCVE-0-2026-21509)

Vulnerability from cvelistv5 – Published: 2026-01-26 17:06 – Updated: 2026-07-30 20:47

Title

Microsoft Office Security Feature Bypass Vulnerability

Summary

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

SSVC

Exploitation: active Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-01-26 00:00 UTC

CWE

CWE-807 - Reliance on Untrusted Inputs in a Security Decision

Assigner

microsoft mitre root

References

4 references

URL	Tags
https://msrc.microsoft.com/update-guide/vulnerabi…	vendor-advisorypatch
https://www.cisa.gov/known-exploited-vulnerabilit…	government-resource
https://www.vicarius.io/vsociety/posts/cve-2026-2…
https://www.vicarius.io/vsociety/posts/cve-2026-2…

Impacted products

5 products

Vendor	Product	Version
Microsoft	Microsoft 365 Apps for Enterprise	Affected: 16.0.1 , < https://aka.ms/OfficeSecurityReleases (custom)
Microsoft	Microsoft Office 2016	Affected: 16.0.0 , < 16.0.5539.1001 (custom)
Microsoft	Microsoft Office 2019	Affected: 19.0.0 , < 16.0.10417.20095 (custom)
Microsoft	Microsoft Office LTSC 2021	Affected: 16.0.1 , < https://aka.ms/OfficeSecurityReleases (custom)
Microsoft	Microsoft Office LTSC 2024	Affected: 16.0.0 , < https://aka.ms/OfficeSecurityReleases (custom)

Date Public

2026-01-26 16:00

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
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        "metrics": [
          {
            "other": {
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                "id": "CVE-2026-21509",
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                "role": "CISA Coordinator",
                "timestamp": "2026-01-26T00:00:00+00:00",
                "version": "2.0.3"
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          },
          {
            "url": "https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability"
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    "dateReserved": "2025-12-30T18:10:54.844Z",
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  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

BDU:2026-00828 (CVE-2026-21509)

CVE-2026-21509 (GCVE-0-2026-21509)

Tags

Sightings

Nomenclature

Related by attack behaviour