Firefox 78 End of Life Date
Firefox 78 end-of-life date, support status, and CVE risk. Data from endoflife.date and official vendor documentation.
Firefox 78 was released on June 30, 2020 and support ended on November 2, 2021 — a supported lifespan of 1 year and 4 months, in line with the 1 year and 3 months median for Firefox LTS releases. It was a long-term support (LTS) release, so it received a longer patch window than the interim releases around it. The last patch it will ever receive is 78.15.0, published October 5, 2021 — 28 days before support ended. It has been without security patches for 4 years and 9 months. 52 newer Firefox releases have shipped since.
What does Firefox 78 end of life mean?
When Firefox 78 reaches end of life, the maintainers stop issuing security patches for this version. CVEs discovered after the EOL date are publicly disclosed on the National Vulnerability Database with no patch available. Exploit code frequently appears on GitHub within days of disclosure.
The CVE blind spot: Most vulnerability scanners check for known CVEs but do not flag the ongoing accumulation of unpatched vulnerabilities in EOL software versions. Running Firefox 78 past its EOL date creates a permanently growing attack surface that standard security tooling will not surface.
Migrate to Firefox 153 or implement compensating controls — network segmentation, enhanced monitoring, restricted access — while migration is underway.