Websites are only as safe as their operators allow them to be. Researchers find vulnerabilities, and organizations release patches for them all the time. But it's up to site operators to install those patches to make sure their sites don't endanger visitors and, potentially, their personal information. Many don't, as Northeastern University discovered when it found that 37% of sites use outdated JavaScript libraries with at least one known vulnerability.
The Northeastern University researchers scanned 75,000 of Alexa top websites and 75,000 more websites randomly taken from "a snapshot of the .com zone in May 2016." They found that more than one-third of Alexa's top websites use one JavaScript library with a known vulnerability. Another 10% use two or more libraries with known security problems. Roughly 97% of the sites wouldn't be able to fix all their vulnerabilities with a few quick patches.
This means that many website operators who haven't bothered to regularly patch their JavaScript libraries will now have to install whole new libraries to address all their security vulnerabilities. That seems unlikely at best--many of these websites use outdated libraries for a reason, and it's probably not because their owners are infatuated with old tech. It's most likely because the sites have been abandoned or simply aren't made with security in mind.
Not that JavaScript library creators and maintainers have made things easier for website operators. As the researchers said in their paper, titled Thou Shalt Not Depend on Me: Analysing the Use of Outdated JavaScript Libraries on the Web:
Perhaps our most sobering finding is practical evidence that the JavaScript library ecosystem is complex, unorganised, and quite 'ad hoc' with respect to security. There are no reliable vulnerability databases, no security mailing lists maintained by library vendors, few or no details on security issues in release notes, and often, it is difficult to determine which versions of a library are affected by a specific reported vulnerability.
Those aren't small problems. The researchers said that 87.7% of Alexa websites and 46.5% of the randomly selected websites use "at least one well-known JavaScript library" such as jQuery, Handlebars, and Angular, among others. These open source libraries are used by millions of sites that weren't analyzed by Northeastern University; it's hard to imagine that you've never visited a site that uses at least one of them.
Vulnerabilities in these and other JavaScript libraries can cause all sorts of headaches. Website operators might worry about someone exploiting a vulnerability to inject code on their site; you might worry more about someone abusing a security flaw to gather your personal information. The researchers explained:
Attackers can use these capabilities to steal data from a user’s browsing session, initiate transactions on the user’s behalf, or place fake content on a website. Therefore, JavaScript libraries must not introduce any attack vectors into the websites where they are used.
None of that sounds like fun. But the researchers also found that many popular JavaScript libraries don't share any security problems with devs:
During this entire work, we did not encounter a single popular library that had a dedicated mailing list for security announcements (in fact, most libraries we investigated did not have a mailing list for announcements at all). Furthermore, only a few JavaScript library developers provide a dedicated email address where users can submit vulnerability reports. When the release notes of libraries mention at all that a vulnerability has been fixed, they often do not provide any details about the affected code, or which prior versions are vulnerable.
The end result: nigh ubiquitous JavaScript libraries that don't help website operators keep you safe. The websites themselves, their users, and personal information about an untold number of people could all be vulnerable to attack simply because developers didn't know they were using outdated JavaScript libraries or weren't sure if using an old version of the tech would undermine their website's security.
