Details ================ Software: YouTube Embed Version: 3.3.2 Homepage: https://wordpress.org/plugins/youtube-embed/ CVE ID: CVE-2015-6535 (Pending) CWE ID: CWE-79 CVSS: 5.5 (Medium; AV:N/AC:L/Au:S/C:P/I:P/A:N) Description ================ A stored XSS vulnerability in YouTube Embed 3.3.2 (and possibly earlier versions) allows admin users to compromise other admins and super admins. YouTube Embed is a WordPress plugin with over 30,000 active installs. Vulnerability ================ Admins on multisite installs can inject arbitrary JavaScript into pages visible to super admins via the plugin's unsanitized profile name field. Note: Admins on multisite installs lack the unfiltered_html capability – only super admins can enter unfiltered html [2]. >From youtube-embed/includes/options-profiles.php: 31: $options[ 'name' ] = $_POST[ 'youtube_embed_name' ]; … 95: echo '<div class="updated fade"><p><strong>' . __( $options[ 'name' ].' Profile Saved.' ) . "</strong></p></div>\n"; Proof of concept ================ 1. As an admin user authorized for plugins, go to the YouTube Embed Profiles page. 2. Choose a profile from the drop down list on the right and click 'Change profile'. 3. Enter an XSS payload (e.g. <script>alert(1)</script>) into the 'Profile name' field. 4. Log out and log in as a super admin or a different admin. 5. Navigate to the YouTube Embed Options page. This has been tested with Firefox 38.2.0 on Debian. Mitigation ================ Upgrade the plugin to version 3.3.3 or later. Timeline ================ 2015-08-19: Discovered 2015-08-19: Requested vulnerability reporting instructions via vendor support form 2015-08-20: Vendor asked that vulnerability be reported on the vendor's website plugin page 2015-08-20: Reported to vendor via plugin page 2015-08-20: Requested CVE number 2015-08-23: Vendor released version 3.3.3 – confirmed fixed 2015-08-26: Public Disclosure References ================ [1] https://wordpress.org/plugins/youtube-embed/changelog/ [2] https://codex.wordpress.org/Roles_and_Capabilities#Additional_Admin_Capabilities