CVE-2026-19902
Description
The Ad Inserter – Ad Manager & AdSense Ads plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the Referer header in all versions up to, and including, 2.8.18 due to insufficient input sanitization and output escaping on the '{search-query}' dynamic tag. When an ad block's code contains that tag, replace_ai_tags() reads $_SERVER['HTTP_REFERER'] and tests it with the regex /[\.\/](google|yahoo|bing|ask)\.[a-z\.]{2,5}[\/]/i. The leading [\.\/] class matches a literal slash, so any referrer merely containing a segment such as '/google.com/' passes as a search-engine referral; the plugin then percent-decodes the referring query with parse_str() and substitutes the resulting 'q' (or 'p') value into the block via preg_replace() with no escaping. This makes it possible for unauthenticated attackers to execute arbitrary JavaScript in the context of the site for any visitor, including a signed-in administrator, by luring them to an attacker-controlled page that frames or links to any ordinary post. Exploitation requires the site to have an ad block whose code uses the '{search-query}' tag with automatic insertion enabled — a documented plugin feature used as intended.
Affected WordPress components
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Ad Inserter – Ad Manager & AdSense Ads Plugin · ad-inserterUp to and including 2.8.18View on WordPress.org
A confirmed match is backed by the plugin or theme slug. A possible match is based on the product name only and should be verified.
Affected products and versions
- spacetime Ad Inserter – Ad Manager & AdSense Ads — Up to and including 2.8.18
References
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/ad-inserter/tags/2.8.18/ad-inserter.php#L13018
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/ad-inserter/tags/2.8.18/ad-inserter.php#L13022
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/ad-inserter/tags/2.8.18/ad-inserter.php#L13025
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/ad-inserter/tags/2.8.18/ad-inserter.php#L13093
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/ad-inserter/tags/2.8.18/class.php#L3297
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/changeset/3709957/ad-inserter/trunk/ad-inserter.php
- plugins.trac.wordpress.org https://plugins.trac.wordpress.org/changeset?reponame=&new=3709970%40ad-inserter%2Ftags%2F2.8.19&old=3624916%40ad-inserter%2Ftags%2F2.8.18
- www.wordfence.com https://www.wordfence.com/threat-intel/vulnerabilities/id/5d632cce-40a9-4969-b213-8370ae75287e?source=cve
- nvd.nist.gov Official NVD record