Question 1

What is the EOL Risk Score for Microsoft Exchange 2013 CU23 SU21?

Accepted Answer

Microsoft Exchange 2013 CU23 SU21 has an EOL Risk Score™ of 70 out of 100, placing it in the High risk band. The score is calculated from four factors: EOL Recency (40/40), Attack Surface (10/30), CISA KEV Exposure (20/20), and Extended Support Availability (0/10).

Question 2

Is Microsoft Exchange 2013 CU23 SU21 still supported?

Accepted Answer

Microsoft Exchange 2013 CU23 SU21 is no longer supported — it has passed its end of life date (April 11, 2023). No further security patches will be issued. Upgrade to a supported version or obtain extended lifecycle support.

Question 3

When does Microsoft Exchange 2013 CU23 SU21 reach end of life?

Accepted Answer

Microsoft Exchange 2013 CU23 SU21 reached (or will reach) end of life on April 11, 2023. After this date, no security patches or bug fixes are issued by the vendor.

Question 4

What are the security risks of running Microsoft Exchange 2013 CU23 SU21 after end of life?

Accepted Answer

After end of life, Microsoft Exchange 2013 CU23 SU21 no longer receives security patches. Any newly discovered CVEs remain unpatched indefinitely. Organizations running EOL software also face compliance violations under SOC 2, PCI DSS, HIPAA, and ISO 27001, which require use of supported software versions.