Trouble Updating TimThumb after Vulnerability Discovered

Hi,

I’m trying to update my theme’s installation of TimThumb after the news came out that there is a security breach – https://markmaunder.com/2011/zero-day-vulnerability-in-many-wordpress-themes/

Problem is, when I tried to overwrite the TimThumb.php file with the new code, my site’s thumbnails stopped working. Is there something else in that PHP file that I need to change?

I’m not very familiar with PHP, so I’d appreciate whatever help anyone can provide!

I’ve uploaded the code to a pastebin for review.

New TimThumb.php code: https://pastebin.com/Tb4j24ZX

Current & Unsecure PHP Code: https://pastebin.com/REUUZMQQ

Thanks so much!