Google and Mozilla both pushed security updates for their browsers on 27 October, fixing more than 200 vulnerabilities between them. Both are worth installing straight away.
Google's new Stable channel release brings desktop Chrome to version 156.0.8078.73/.74 on Windows and Mac and 156.0.8078.73 on Linux. It includes 52 security fixes, four of them rated Critical. The same day, Mozilla published Security Advisory 2026-118, which fixes 167 vulnerabilities and ships with Firefox 159. Both updates roll out gradually over the coming days and weeks, as summarised by Malwarebytes Labs. The vendors' own release notes and advisory carry the per-bug detail and severity ratings.
Memory bugs in layout, JavaScript and SVG
According to Malwarebytes, both releases fix use-after-free vulnerabilities, a class of bug where a program keeps using a piece of memory after it has been released. That can crash the browser or, in some cases, let an attacker run their own code. The fixed flaws include problems in page layout, JavaScript processing and SVG graphics handling. Malwarebytes' summary does not report any of them as exploited in the wild.
There is another thread connecting the two releases: both Google and Mozilla credit OpenAI Codex Security with finding some of the bugs fixed this time. AI-assisted code review is now showing up in browser credits from more than one vendor, alongside human review and fuzzing.
Update to Chrome 156.0.8078.73 and Firefox 159.0
Chrome updates itself, but a browser that is never closed, or an extension that blocks the update, can leave you behind. Open About Google Chrome from the settings or Help menu, let it check, and click Relaunch. In Firefox, open the menu, go to Help, choose About Firefox, and relaunch once the download finishes. You should see version 159.0 or later. Administrators should push both builds through their usual browser management tooling.
This is the browsers' regular rhythm rather than an emergency, and that is the point: the last round, covered in Chrome 155's 37 fixes and the earlier same-day Chrome and Firefox patch drop, was only weeks ago. Keeping up with that cadence is the cheapest security control most people have.
This briefing is provided by IntelFusions for informational and defensive purposes only. It is based on sources assessed to be reliable at the time of writing, and analytic judgments carry the confidence levels indicated. Indicators of compromise are defanged; re-arm them only in controlled environments. IntelFusions is not affiliated with the organizations named and makes no warranty as to completeness or accuracy.