Is it safe to use an old MacBook which no longer gets software updates

Apple is still providing some security updates for Monterey until near the end of 2024, but only for the more severe vulnerabilities. Apple provides limited security updates to the two most recent versions of macOS. At this time, Sonoma is the current OS while Apple will still supply some limited security updates to Ventura (near end of 2025)and Monterey (near end of 2024).

Whether that is an issue depends upon your circumstances. For the average person it is not that big of a deal especially if the user practices safe computing practices as outlined in this article written by a respected forum contributor:

Effective defenses against malware and other threats - Apple Community

Just make sure to use a third party browser instead of Safari since third party browsers will be still receiving updates, but Safari will stop receiving all updates near the end of 2024.

If you require as much security as possible, then it would seem you would need to get another laptop with a fully supported OS. Usually this is only needed if your job is very sensitive or you are a target for attack. For most other people the above tips should be sufficient to keep them reasonably safe.

Is it safe? If you never go online with it.

If you do go online with an unsupported OS, there are definitely risks. As HWTech mentioned, using a browser that is still receiving security updates is an excellent mitigation. I’d also recommend sticking to really reputable sites and using bookmarks, because it’s EASY to mistype a website and end up somewhere that can infect your machine. Also, avoid clicking on advertisements, especially ones on news sites, recipe sites, and song-lyric sites. If that sounds oddly specific, there’s a reason for it.

About security. An important part of security is the use of passwords. Passwords for web sites, access to networks and to modems. Passwords used should be varied and complex. The more complex and varied, the greater security. People here on this forum regularly report that they "forgot" their Mac's access password and can't open it. That is pretty sad to me. I keep an Excel spreadsheet with all my IDs and passwords for each site. It is kept up-to-date. I print it out for easy reference when needed. It too is password protected.

Mostly you just need a more modern Browser than Safari on Catalina, Mojave, or High Sierra like Firefox or Brave.

https://brave.com/

Opera…Thanks

https://www.opera.com/download/requirements

Opera system requirements | Opera

Thanks to dialabrain…

Firefox 115 is now the current version. runs in High Sierra.

119.0.1 is now the current version and requires 10.15 or later.

https://www.mozilla.org/en-US/firefox/new/

Thanks to A Brody, Browsers by Mac operating system…

Browsers by Mac operating system - Apple Community

Monterey (12.x) will continue to receive security updates at a minimum until macOS 15 is released. Apple's official policy is to support the current version of macOS + the 2 previous versions. They are currently Sonoma, Ventura & Monterey. Even after a macOS 15 is released, Apple may issue security updates for Monterey if there is a significant security risk to be managed.

Beyond that, there are no significant security risks unless you yourself are doing risky things with your computer (like visiting certain types of websites, using torrent servers, installing pirated software, not watching out for pfishing, etc.)

For additional protection, consider installing Malwarebytes. There is a free version and a paid version. You should also consider installing installing privacy/security-related plugins for your browser, such as Privacy Badger & uBlock Origin.

Running Windows on a Mac, and Connecting … - Apple Community

Boot Camp may be gone on 2020 and newer Macs, but VMware, Parallels and CrossOver each offer their own ARM Windows options on newer Macs. Newer Macs also support iOS Apps.

You may also want to find out what software is available for Mac OS that does the work you normally do in Windows. It may even be able to read the document format you are looking to work with.

Thank you. That’s at least somewhat helpful. I have a 2015 MBP which I plan on upgrading once security updates are no longer available (despite having a third party security tool). Now if we could only get around the intel/ARM architecture issues for VM’s. I’ve been half heartedly looking to V->P my old win 10 VM so I can keep my legacy software investment.