FCKedtior 2.6.10 Reflected Cross-Site Scripting (XSS)

Class Cross-Site Scripting
Remote Yes
Published 2nd June 2014
Credit Robin Bailey of Dionach ([email protected])
Vulnerable FCKeditor <= 2.6.10

FCKeditor is prone to a reflected cross-site scripting (XSS) vulnerability due to inadequately sanitised user input. An attacker may leverage this issue to run JavaScript in the context of a victim's browser.

FCKeditor 2.6.10 is known to be vulnerable; older versions may also be vulnerable.

Note that this issue is related to CVE-2012-4000, which was a cross-site scripting vulnerability in the values of the textinputs[] array passed to the spellchecker.php page. To resolve this issue the values of this array were encoded with htmlspecialchars() before being output to the page; however the array keys were still echoed unencoded.

PoC:

POST http://[target]/editor/dialog/fck_spellerpages/spellerpages/server-scripts/spellchecker.php
textinputs[1</script><script>alert(document.cookie);//</script>]=zz

The vendor was notified of this issue, and FCKeditor 2.6.11 was released to address this vulnerability. See the following vendor announcement:

http://ckeditor.com/blog/FCKeditor-2.6.11-Released

Timeline:

28/05/2014 Vulnerability identified
28/05/2014 Initial vendor contact
28/05/2014 Vendor response to contact
28/05/2014 Vulnerability disclosed to vendor
29/05/2014 Vendor confirms vulnerability
02/06/2014 Vendor releases patch
02/06/2014 Public disclosure of vulnerability

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