“Microsoft ended support for Office 2021 in October, and 0patch provides third-party security patches.”

Microsoft will officially cease providing security and technical support for products such as Office LTSC 2021 starting October 13, 2026. In response to this situation, third-party security company 0patch has announced that it will provide critical vulnerability patches for Office 2021 for at least three years from now. This service is included in its PRO and Enterprise payment plans, with the annual fee for the enterprise version being approximately 273 yuan. The services provided by 0patch do not require users to restart their systems or modify the original programs, but they only cover security fixes and do not include official technical support. Microsoft clearly states that Office 2021 is not eligible for the Extended Security Update (ESU) program. Affected users can choose to upgrade to Microsoft 365 or Office 2024, or switch to alternative software such as LibreOffice.