Microsoft has released its September 2026 security updates addressing 966 vulnerabilities, including 105 Critical vulnerabilities and two actively exploited zero-day vulnerabilities, CVE-2026-81963  and CVE-2026-85880. These vulnerabilities may allow unauthorized access or elevated control of affected systems.

These updates apply to, but are not limited to:

• Windows OS: 11.

• Windows Server: 2022, 2025

• Microsoft Office 2021, 2024

• Exchange Server Subscription Edition(SE)

• Microsoft SQL Server: 2022, 2025

• Microsoft 365 and Microsoft Edge

Security Risks

Successful exploitation of these vulnerabilities may allow threat actors to execute malicious code, escalate privileges, access sensitive information, bypass security protections, or gain unauthorized control of affected systems.  For the full list of security patches released by Microsoft, please refer to the  Microsoft Security Update Guide and apply the necessary updates.

Recommended Actions

The National Cyber Security Authority (NCSA) recommends users and administrators:

1. Apply the latest security patches as soon as possible to prevent unauthorized control over unpatched systems.

2. Upgrade immediately to the latest supported version of installed Microsoft software to continue receiving technical support and security patches.

The following Microsoft software products reached their end-of-life and need to be upgraded soon:

• Windows Server 2003, 2003 RE, 2008, 2008 RE, 2008 SP2, 2012, and 2012 R2

• Exchange Server 2003, 2007, 2010, 2013, 2016, 2019, and Windows Vista, XP, 8, and 7, 10.

• Microsoft SQL Server 2005, 2008, 2012, 2014, 2016 and MS Office 2013, 2016 and 2019.

       Upcoming End‑of‑Life: 

• Office 2021: October 13, 2026. Upgrade to a supported version before this date.

For more information, including other products reaching end-of-support in 2026, see Microsoft’s official documentation.

3. Before any updating task, ensure you have a current, tested backup of your data.

For further information and support, please contact the National Cyber Security Authority (NCSA) by emailing rwcsirt@ncsa.gov.rw or calling us on 9009.

References

• Microsoft September 2026 Security Release Notes

• Microsoft September 2026 Patch Tuesday fixes 966 flaws, 2 zero-days

• Released: September 2026 Exchange Server Security Updates