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Firefox 156 security update: restart to finish installation
Firefox 156 includes security fixes rated high impact by Mozilla. Check the installed version and restart Firefox to finish applying the update.
Mozilla released Firefox 156 on September 15 with security fixes rated high impact in its advisory. The list includes memory-safety issues, privilege escalation and sandbox escapes. Mozilla identifies Firefox 156 as the version containing the fixes; individual issues can affect different components or platforms.
Check the update and restart
Open the Firefox menu, choose Help, then About Firefox. Firefox checks for an update there and offers a restart after the download. On macOS, use the Firefox menu. If Firefox came from the Microsoft Store or a Linux distribution repository, update it through that store or package manager; availability can depend on the distributor.
How Mozilla lists the issues
Mozilla now gives internally identified memory-safety bugs their own advisories instead of grouping them under one CVE. The number of advisory entries reflects that reporting change and the bugs fixed in a release.
Release cadence
Mozilla moved to a two-week major-release cycle with Firefox 155 on September 1. Mozilla says the schedule delivers completed work sooner.