Details ================ Software: WP User Groups Version: 2.0.0 Homepage: https://wordpress.org/plugins/wp-user-groups/ Advisory report: https://advisories.dxw.com/advisories/csrf-wp-user-groups/ CVE: Awaiting assignment CVSS: 4.3 (Medium; AV:N/AC:M/Au:N/C:N/I:P/A:N) Description ================ CSRF in WP User Groups allows anybody to modify user groups and types Vulnerability ================ WP User Groups creates new bulk actions to put users into (or remove them from) agroupsa and atypesa. A nonce is sent with the request, but it is not checked. Proof of concept ================ Activate the plugin Make sure you have a user with user_id=1 Visit http://localhost/wp-admin/edit-tags.php?taxonomy=user-group and create a group called aCata with slug acata Visit http://localhost/wp-admin/users.php?users%5B%5D=1&action2=add-cat-user-group If you go back to http://localhost/wp-admin/users.php youall see the user with user_id=1 is now in the group aCata Mitigations ================ Upgrade to version 2.1.1 or later. Disclosure policy ================ dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/ Please contact us on security@dxw.com to acknowledge this report if you received it via a third party (for example, plugins@wordpress.org) as they generally cannot communicate with us on your behalf. This vulnerability will be published if we do not receive a response to this report with 14 days. Timeline ================ 2018-04-12: Discovered 2018-04-16: Reported to plugin author via email 2018-04-16: Vendor reported fixed in 2.1.1 2018-05-11: Advisory published Discovered by dxw: ================ Tom Adams Please visit security.dxw.com for more information.