phpMyFAQ sharing FAQ functionality can easily be abused for phishing purposes

Vulnerability Description

phpMyFAQ is an Open Source FAQ web application for PHP 8.1+ and MySQL, PostgreSQL and other databases. The 'sharing FAQ' functionality allows any unauthenticated actor to misuse the phpMyFAQ application to send arbitrary emails to a large range of targets. The phpMyFAQ application has a functionality where anyone can share a FAQ item to others. The front-end of this functionality allows any phpMyFAQ articles to be shared with 5 email addresses. Any unauthenticated actor can perform this action. There is a CAPTCHA in place, however the amount of people you email with a single request is not limited to 5 by the backend. An attacker can thus solve a single CAPTCHA and send thousands of emails at once. An attacker can utilize the target application's email server to send phishing messages. This can get the server on a blacklist, causing all emails to end up in spam. It can also lead to reputation damages. This issue has been patched in version 3.2.5.

References

• https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-9hhf-xmcw-r3xg
• https://github.com/thorsten/phpMyFAQ/commit/a34d94ab7b1be9256a9ef898f18ea6bfb63f6f1e