and ignored the word “fixed”, wich usually implies: No known danger, if you use a version higher or same than the one named there as fixed.
Nobody but you can check on this. For example when there was a security issue with LibreLogo I did actually nothing in my company, as I had not installed this part. Others may need to update.
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You have also to know of the risks for your environment: We use an old laptop with XP. Not risky at all, because it is used as a big calculator, with a 30 years old .xls-file. Not connected to anything and will be used until it breaks…But it would have an impressive cve-list. So if you construct a lunar lander you may have different needs than sombody using a tax-calculator.
… and you have addressed all CVE-“risks” of your xlsx-producing software and the OS? If your system is secured like that, don’t change anything.
My first idea is to recommend a pen (not to sharp), then reminding you “fixed in” means “yes, there is a solution available”.
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On a general scale, LibreOffice like any big bundles of code will always have to address security concerns, but developers do and we have to update, if our “profile” is affected. If you use Windows and MS-Office, there are bigger problems lurking than LibreOffice. If you are really concerned about security, then consider cubesOS, but as usual: Security comes with the price of reduced convenience.