WordPress 3.8.1 / 3.8.2 / 4.2.2 Cross Site Request Forgery

`Details  
================  
Software: WordPress  
Version: 3.8.1,3.8.2,4.2.2  
Homepage: http://wordpress.org/  
Advisory report: https://security.dxw.com/advisories/comment-form-csrf-allows-admin-impersonation-via-comments-in-wordpress-4-2-2/  
CVE: Awaiting assignment  
CVSS: 4.3 (Medium; AV:N/AC:M/Au:N/C:N/I:P/A:N)  
  
Description  
================  
Comment form CSRF in WordPress 4.2.2 allows admin impersonation via comments  
  
Vulnerability  
================  
When posting comments,WordPress does not require a nonce value (unless posting unfiltered HTML). This means that an attacker can force a logged-in user to post arbitrary comments.  
For this to happen, the logged-in user would have to be tricked into clicking on a link controlled by the attacker. It is easy to make these links very convincing.  
The line which verifies the nonce when using unfiltered HTML is line 154 of wp-comments-post.php.  
EDIT: this issue has been known about since 2009, but it appears that no fix is planned https://core.trac.wordpress.org/ticket/10931  
  
Proof of concept  
================  
Log in, visit an URL containing the following (replacing localhost as appropriate, replacing 1 with the ID of a post), click submit:  
<form method=\"POST\" action=\"http://localhost/wp-comments-post.php\">  
<input type=\"text\" name=\"comment_post_ID\" value=\"1\">  
<input type=\"text\" name=\"comment\" value=\"UH OH\">  
<input type=\"submit\">  
</form>  
  
(In a real attack the form can be made to auto-submit using Javascript)  
  
Mitigations  
================  
Disable comments until a new version is released that fixes this bug  
  
Disclosure policy  
================  
dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/  
  
Please contact us on [email protected] to acknowledge this report if you received it via a third party (for example, [email protected]) 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  
================  
  
2009-10-19: Ticket raised by mtdewvirus  
2014-03-20: Discovered independently by dxw  
2015-07-14: Reported to [email protected]  
2015-07-14: Requested CVE  
2015-07-17: Response from [email protected]  
2015-08-05: Published  
  
  
  
Discovered by dxw:  
================  
Tom Adams  
Please visit security.dxw.com for more information.  
  
  
  
  
`