Firefox 155 End of Life Date
Firefox 155 end-of-life date, support status, and CVE risk. Data from endoflife.date and official vendor documentation.
Firefox 155 was released on September 1, 2026 and has no published end-of-life date yet. It is not an LTS release; Firefox reserves longer patch windows for its LTS versions. Its most recent patch is 155.0, published September 1, 2026.
What does Firefox 155 end of life mean?
When Firefox 155 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 155 past its EOL date creates a permanently growing attack surface that standard security tooling will not surface.
Migrate to Firefox 155 or implement compensating controls — network segmentation, enhanced monitoring, restricted access — while migration is underway.