Prepared by the Nadali editorial team using AI
On 27 October 2026, Mozilla released stable Firefox 159. Advisory MFSA2026-118 rates the overall impact of the fixed issues as high. They include sandbox escapes and privilege escalation. The version containing the fixes is Firefox 159.
Who benefits and what changes
Owners of shops, hotels and service businesses whose employees use Firefox for email, bookings or administration portals. Our editorial takeaway: check the version actually installed on work devices. A release announcement alone does not confirm that the team has received the fixes.
What to do
Mozilla’s instructions say to open Help → About Firefox for a regular installation; on Mac, use Firefox → About Firefox. Allow an available update to download and restart the browser. Microsoft Store installations update through the Store; Linux distribution packages through the distribution’s tools.
This is an editorial checklist, not the result of testing by Nadali:
- Identify work computers using Firefox and assign an owner.
- Save unfinished work and complete any orders in progress before restarting.
- Reopen the browser information after updating; record the version and check date.
- Check familiar work pages without making a real payment or sending customer data.
- For managed devices or the separate ESR channel, agree the required version with the IT owner; do not change channels by guessing.
Limits
The advisory does not establish that your business has been attacked. Nadali has not tested the fixes or inspected readers’ devices. This article concerns a security update, not availability of new AI features.
For other work browsers, see our separate Chrome 156 update check.
Sources checked on 27 October 2026. Cover: a reused Nadali AI illustration, not a Firefox interface or a photograph of an event.
