## SPIP 3.1.2 Reflected Cross-Site Scripting (CVE-2016-7981) ### Product Description SPIP is a publishing system for the Internet, which put importance on collaborative working, multilingual environments and ease of use. It is free software, distributed under the GNU/GPL licence. ### Vulnerability Description The `var_url` parameter of the `valider_xml` file is not correctly sanitized and can be used to trigger a reflected XSS vulnerability. **Access Vector**: remote **Security Risk**: medium **Vulnerability**: CWE-79 **CVSS Base Score**: 6.8 (Medium) **CVE-ID**: CVE-2016-7981 ### Proof of Concept http://spip-dev.srv/ecrire/?exec=valider_xml&var_url=%22%3E%3Ch1%3EXSS!%3C/h1%3E ### Vulnerable code The `$url variable` is not properly sanitized in `valider_xml.php`, line 134 : $res = "<div style='text-align: center'>" . $err . "</div>" . "<div style='margin: 10px; text-align: left'>" . $texte . '</div>'; $bandeau = "<a href='$url_aff'>$url</a>"; The Cross-Site Scripting vulnerability is triggered on line 146 : echo "<h1>", $titre, '<br>', $bandeau, '</h1>', ### Timeline (dd/mm/yyyy) * 15/09/2016 : Initial discovery * 26/09/2016 : Contact with SPIP Team * 27/09/2016 : Answer from SPIP Team, sent advisory details * 27/09/2016 : Incorrect fix from SPIP Team. * 27/09/2016 : New proof of concept for bypassing fixes for XSS sent. * 27/09/2016 : Fixes issued for XSS (23185). * 30/09/2016 : SPIP 3.1.3 Released ### Fixes * https://core.spip.net/projects/spip/repository/revisions/23200 * https://core.spip.net/projects/spip/repository/revisions/23201 * https://core.spip.net/projects/spip/repository/revisions/23202 ### Affected versions * Version <= 3.1.2 ### Credits * Nicolas CHATELAIN, Sysdream (n.chatelain -at- sysdream -dot- com) -- SYSDREAM Labs <labs@sysdream.com> GPG : 47D1 E124 C43E F992 2A2E 1551 8EB4 8CD9 D5B2 59A1 * Website: https://sysdream.com/ * Twitter: @sysdream