> I don't understand how something like this could take so long to be discovered.

Maybe they wrote it in C :-)

On a serious note, old software is generally more trustworthy than new software, because bugs are discovered over time and with usage.

Old C software is generally more trustworthy than new C software. I don't think this rule of thumb transfers across languages very well. And the definition of new vs old has a fairly large effect. If a language has been under constant change it doesn't matter when it was started a large part of the codebase is "new".