CVE-2021-4424: 
WordPress vulnerability analysis and mitigation

The Slider Hero WordPress plugin (versions up to and including 8.2.0) contains a Cross-Site Request Forgery (CSRF) vulnerability identified as CVE-2021-4424. The vulnerability exists due to missing or incorrect nonce validation in the qcsliderhero_duplicate() function, which allows unauthenticated attackers to duplicate slides through forged requests if they can trick a site administrator into performing specific actions (NVD).

The vulnerability stems from improper implementation of WordPress security nonces in the qcld-slider-main.php file. Specifically, the security check only verifies the nonce if $REQUEST['sliderheroduplicatenonce'] is set, allowing attackers to bypass the security check by omitting the nonce parameter entirely (NinTechNet Blog). The vulnerability has been assigned a CVSS v3.1 Base Score of 4.3 (Medium) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N (Wordfence).

If successfully exploited, this vulnerability allows attackers to duplicate slides in the Slider Hero plugin by tricking administrators into clicking on malicious links. While the impact is limited to slide duplication functionality, it could potentially be used to create confusion or resource consumption issues on affected sites (NVD).

The recommended mitigation is to update the Slider Hero plugin to a version newer than 8.2.0, which includes the security fix. The fix implements proper nonce validation for the slide duplication functionality (NinTechNet Blog).