For our 24th security review of a WordPress plugin based on the voting of our customers, we reviewed the plugin Co-Authors Plus.
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The review was done on version 3.3.1 of Co-Authors Plus. We checked for the following issues during this review:
- Insecure file upload handling (this is the cause of the most exploited type of vulnerability, arbitrary file upload)
- Deserialization of untrusted data
- Security issues with functions accessible through WordPress’ AJAX functionality (those are a common source of disclosed vulnerabilities these days)
- Persistent cross-site scripting (XSS) vulnerabilities in the frontend portions of the plugin and in the admin portions accessible to users with the Author role or below
- Cross-site request forgery (CSRF) vulnerabilities in the admin portion of the plugin
SQL injection vulnerabilities (the code that handles requests to the database)
Reflected cross-site scripting (XSS) vulnerabilities
- Security issues with functions accessible through any of the plugin’s shortcodes
- Security issues with functions accessible through the admin_action action
- Security issues with functions accessible through the admin_init action
- Security issues with import/export functionality
- Security issues with usage of is_admin()
- Security issues with usage of add_option(), delete_option(), and update_option()
- Host header injection vulnerabilities
Lack of protection against unintended direct access of PHP files
- Insecure and unwarranted requests to third-party websites
- Any additional possible issues identified by our Plugin Security Checker
We found one really minor issue.
Lack of Protection Against Direct Access to PHP Files
The plugin’s .php files not intended to be directly accessed but do not contain protection against direct access. We didn’t see anything that could be exploited in the files without the restriction in place.