I'm struggling to understand how there can be so many security flaws, even in things that don't seem to matter for security. I think the bar for a security problem might be too low; a lot of these look like footguns that could give my package a security hole, rather than genuine security flaws in the packages they are reported on.

Here's a progress bar package with a "high" security vulnerability because it contains an internal utility that merges objects and doesn't stop you writing to the prototype. Did the progress bar package ever promise to provide an object merge function that was safe to use on untrusted user input?

Here's a notification UI element that bills using HTML in your notification messages as a feature. It has a "medium" level "XSS" security vulnerability where the message parameter is not sanitized to remove HTML. A CVE was issued for this.

Here's an arbitrary code execution vulnerability in sqlite3! High severity! The bug is that, if you tell sqlite3 to substitute an object into an SQL statement, it will run the ToString() method on the object. If an evil hacker has broken into your lead developer's house and written a malicious ToString() method into one of the classes of object you use as a database query parameter, then that code would run! The fix here was, instead of letting the normal Javascript stringification rules apply, to hardcode all objects to be inserted into the database as "[object Object]", because surely that is what the programmer meant to store.