Question 1

What is the EOL Risk Score for Juniper Junos OS 21.3?

Accepted Answer

Juniper Junos OS 21.3 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 Juniper Junos OS 21.3 still supported?

Accepted Answer

Juniper Junos OS 21.3 is no longer supported — it has passed its end of life date (March 23, 2024). No further security patches will be issued. Upgrade to a supported version or obtain extended lifecycle support.

Question 3

When does Juniper Junos OS 21.3 reach end of life?

Accepted Answer

Juniper Junos OS 21.3 reached (or will reach) end of life on March 23, 2024. After this date, no security patches or bug fixes are issued by the vendor.

Question 4

What are the security risks of running Juniper Junos OS 21.3 after end of life?

Accepted Answer

After end of life, Juniper Junos OS 21.3 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.