Question 1

What is the EOL Risk Score for .NET Framework 4.5.1?

Accepted Answer

.NET Framework 4.5.1 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 .NET Framework 4.5.1 still supported?

Accepted Answer

.NET Framework 4.5.1 is no longer supported — it has passed its end of life date (January 12, 2016). No further security patches will be issued. Upgrade to a supported version or obtain extended lifecycle support.

Question 3

When does .NET Framework 4.5.1 reach end of life?

Accepted Answer

.NET Framework 4.5.1 reached (or will reach) end of life on January 12, 2016. After this date, no security patches or bug fixes are issued by the vendor.

Question 4

What are the security risks of running .NET Framework 4.5.1 after end of life?

Accepted Answer

After end of life, .NET Framework 4.5.1 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.