This can surely cause you a problem in form of either getting your wordpress blog/website hacked etc.
Here’s a solution called “TAC” aka “Theme Authenticity Checker”. What it does is searches the source files of every installed theme for signs of malicious code and if there is such thing, it displays it which you can afterwards check with the author and sort things out.
Tac basically is a wordpress plugin which can be installed easily. After installation, perform a scan on all the themes installed on your blog and it will check for any kind of threats that they might have.