Security update October 21, 2026 High severity

Firefox security update

Firefox 158.0.2 is the newest Firefox security update, with ESR 115.43.1, ESR 140.17 and ESR 153.5.1 for extended support. Earlier versions are missing published fixes.

On a Mac

Anyone who uses Firefox. Firefox updates itself when it restarts; Help › About Firefox checks right away.

The fix

• Firefox 115.43.1, 140.17, 153.5.1 and 158.0.2

Sources

• mozilla.org
• mozilla.org
• mozilla.org
• mozilla.org

From the Briefing, updated 16 minutes ago.