Details
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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
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CSRF in WP User Groups allows anybody to modify user groups and types

Vulnerability
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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
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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
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Upgrade to version 2.1.1 or later.

Disclosure policy
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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
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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:
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Tom Adams
Please visit security.dxw.com for more information.