Question 1

What is the EOL Risk Score for Firefox 151?

Accepted Answer

Firefox 151 has an EOL Risk Score™ of 45 out of 100, placing it in the Medium risk band. The score is calculated from four factors: EOL Recency (25/40), Attack Surface (10/30), CISA KEV Exposure (0/20), and Extended Support Availability (10/10).

Question 2

Is Firefox 151 still supported?

Accepted Answer

Firefox 151 is no longer supported — it has passed its end of life date (June 16, 2026). No further security patches will be issued. Upgrade to a supported version or obtain extended lifecycle support.

Question 3

When does Firefox 151 reach end of life?

Accepted Answer

Firefox 151 reached (or will reach) end of life on June 16, 2026. After this date, no security patches or bug fixes are issued by the vendor.

Question 4

What are the security risks of running Firefox 151 after end of life?

Accepted Answer

After end of life, Firefox 151 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.