Firefox 140 End of Life

Support dates and upgrade guidance — rebuilt from live data.

Supported

Firefox 140 is actively supported. It reaches end of life on 29 Sept 2026.

51 days of security support left

140.13.0 latest release

89% of this branch's supported lifetime has elapsed — 24 Jun 2025 → 29 Sept 2026.

Check your versionfirefox --version

Support timeline

Official dates from the Firefox release process.

Firefox 140 is the newest branch — this is the longest runway currently available.

Branch	End of life	Days left	vs 140
Firefox 140	29 Sept 2026	51	this branch
Firefox 115	31 Mar 2027	234	+183 days

When does Firefox 140 reach end of life?

Firefox 140 reaches end of life on 29 Sept 2026 — 51 days from now. After that date it receives no security fixes.

Is Firefox 140 still supported?

Yes. Firefox 140 is currently maintained. Latest release: 140.13.0, published 21 Jul 2026.

What happens when Firefox 140 reaches end of life?

Security fixes stop. After 29 Sept 2026 this branch receives no further updates under standard support.

How long do I have to upgrade from Firefox 140?

51 days. This is already the newest branch, so this is the longest runway currently available.