The Nextend Social Login and Register plugin for WordPress is vulnerable to a self-based Reflected Cross-Site Scripting via the ‘error_description’ parameter in all versions up to, and including, 3.1.12 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers, with access to a subscriber-level account, to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. NOTE: This vulnerability can be successfully exploited on a vulnerable WordPress instance against an OAuth pre-authenticated higher-level user (e.g., administrator) by leveraging a cross-site request forgery in conjunction with a certain social engineering technique to achieve a critical impact scenario (cross-site scripting to administrator-level account creation). However, successful exploitation requires "Debug mode" to be enabled in the plugin's "Global Settings".

Deserialization of Untrusted Data vulnerability in Nextend Smart Slider 3.This issue affects Smart Slider 3: from n/a through 3.5.1.9.

The Smart Slider 3 WordPress plugin before 3.5.1.14 does not properly validate and escape some of its shortcode attributes before outputting them back in a page/post where the shortcode is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks

Auth. (contributor+) Stored Cross-Site Scripting vulnerability in Nextend Smart Slider 3 plugin <= 3.5.1.9 versions.

The Smart Slider 3 WordPress plugin before 3.5.1.11 unserialises the content of an imported file, which could lead to PHP object injection issues when a user import (intentionally or not) a malicious file, and a suitable gadget chain is present on the site.

The Smart Slider 3 Free and pro WordPress plugins before 3.5.0.9 did not sanitise the Project Name before outputting it back in the page, leading to a Stored Cross-Site Scripting issue. By default, only administrator users could access the affected functionality, limiting the exploitability of the vulnerability. However, some WordPress admins may allow lesser privileged users to access the plugin's functionality, in which case, privilege escalation could be performed.

Cross-site scripting (XSS) vulnerability in the new_Twitter_sign_button function in nextend-Twitter-connect.php in the Nextend Twitter Connect plugin before 1.5.2 for WordPress allows remote attackers to inject arbitrary web script or HTML via the redirect_to parameter. NOTE: this may overlap CVE-2015-4413.

Cross-site scripting (XSS) vulnerability in the new_fb_sign_button function in nextend-facebook-connect.php in Nextend Facebook Connect plugin before 1.5.6 for WordPress allows remote attackers to inject arbitrary web script or HTML via the redirect_to parameter.

Cross-site scripting (XSS) vulnerability in nextend-facebook-settings.php in the Nextend Facebook Connect plugin before 1.5.1 for WordPress allows remote attackers to inject arbitrary web script or HTML via the fb_login_button parameter in a newfb_update_options action.