Can the marks in the review put the page down?

Question

WordPress

I am the owner of a Wordpress site. Site with reviews: people can post reviews, after moderation by the contributor, the reviews are published.

On one of the pages of the site with reviews, a review was posted yesterday, today the contest worker OKnul the review. And after the page did not work (an internal wordpress error was written, or not internal, but "something was a Wordpress error"). That the page lay down I noticed by chance tonight. Because Only one page did not work, I immediately thought that it was a matter of reviews. And deleted the last review. And then immediately the page started working.

I didn't save my review. But I read it briefly before deleting it, there was some kind of smiley or a sign with the use of brackets "<" or ".>" and other characters. Could it put the site down? Is it possible to protect yourself from this?

Answer 1

Is that possible. Especially if the reviews are implemented by a third-party plugin, which may contain errors.
To defend yourself, you need to study the problem. That is, find a problematic review (wait for a repetition), and look at the server error logs to understand what exactly this review breaks in the system.
Proceeding from this, already make a filter that will not let such "malicious" reviews pass, or a filter that will neutralize them.

Answer 2

Offhand, it looks like the recall was either MySQL injection, or js code, or characters that dropped json_decode.
You have to look at what exactly was there.