Firefox 159 End of Life

Support dates and upgrade guidance — rebuilt from live data.

Supported

Firefox 159 is actively supported. It reaches end of life on 10 Nov 2026.

7 days of security support left

159.0 latest release

50% of this branch's supported lifetime has elapsed — 27 Oct 2026 → 10 Nov 2026.

Check your versionfirefox --version

Support timeline

Official dates from the Firefox release process.

Firefox 159 is the newest branch — this is the longest runway currently available.

Branch	End of life	Days left	vs 159
Firefox 159	10 Nov 2026	7	this branch
Firefox 115	31 Mar 2027	148	+141 days

When does Firefox 159 reach end of life?

Firefox 159 reaches end of life on 10 Nov 2026 — 7 days from now. After that date it receives no security fixes.

Is Firefox 159 still supported?

Yes. Firefox 159 is currently maintained. Latest release: 159.0, published 27 Oct 2026.

What happens when Firefox 159 reaches end of life?

Security fixes stop. After 10 Nov 2026 this branch receives no further updates under standard support.

How long do I have to upgrade from Firefox 159?

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