CVE-2026-83591 in AMP for WP Plugin
Summary
by MITRE • 09/25/2026
The AMP for WP – Accelerated Mobile Pages plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content via Regex Transformation in all versions up to, and including, 1.1.16 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The crafted payload uses only WordPress-permitted comment tags and attributes (an anchor with href and title), and the AMP sanitizer pipeline omits javascript: protocol blocking, meaning neither the comment save filter nor the AMP output stage removes the malicious URI introduced by the transformation.
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Analysis
by VulDB Data Team • 09/25/2026
The vulnerability identified in the AMP for WP – Accelerated Mobile Pages plugin represents a significant security risk due to its potential for Stored Cross-Site Scripting attacks within WordPress environments. This flaw exists across all versions up to and including 1.1.16, stemming from insufficient input sanitization and output escaping mechanisms during the processing of comment content. The core technical issue lies in how the plugin handles regex transformations applied to user-generated data before it is stored or rendered on AMP-enabled pages. Because the validation logic fails to adequately restrict malicious inputs, attackers can inject arbitrary web scripts that persist within the database until they are executed by a victim's browser.
The operational impact of this vulnerability allows unauthenticated attackers to compromise the integrity and confidentiality of affected websites without requiring any form of authentication or prior access privileges. By exploiting the regex transformation process, an attacker can craft payloads using only standard WordPress-permitted comment tags and attributes, specifically leveraging anchor elements with href and title properties. This approach is particularly dangerous because it bypasses common security expectations that rely on blocking obvious malicious protocols like javascript:. The AMP sanitizer pipeline, which is designed to ensure content safety for accelerated mobile pages, omits the necessary checks to block such protocol-based injections during its processing stages. Consequently, neither the comment save filter nor the final AMP output stage removes or neutralizes these malicious URIs, allowing them to be served directly to end-users.
From a technical perspective, this vulnerability aligns with CWE-79, which classifies improper neutralization of input during web page generation known as Cross-site Scripting. The specific mechanism involves stored persistence where the injected script is saved on the target server and subsequently delivered to users upon request. This behavior also maps closely to MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution, as well as T1189 Drive-by Compromise if the payload leads to further exploitation such as malware downloads or credential harvesting. The failure of the AMP sanitizer pipeline highlights a gap in the defense-in-depth strategy typically employed by web frameworks that rely on multiple layers of validation and escaping.
Mitigation strategies for this vulnerability require immediate action from site administrators who are running affected versions of the plugin. The most effective remediation is to upgrade the AMP for WP – Accelerated Mobile Pages plugin to version 1.1.17 or later, where these sanitization flaws have been addressed by developers through enhanced input validation and stricter output escaping protocols. In cases where immediate upgrading is not feasible, administrators should consider disabling comment functionality on affected pages as a temporary workaround to prevent the storage of malicious content. Additionally, implementing Web Application Firewalls with rules specifically tuned to detect anomalous regex patterns in comment fields can provide an additional layer of protection against exploitation attempts while patches are being applied. Regular security audits and penetration testing focused on input validation logic are recommended to identify similar weaknesses in other plugins or custom code within the WordPress ecosystem.