Impact Analysis

This vulnerability allows an authenticated attacker with Contributor-level access or higher to inject arbitrary JavaScript code into pages of a WordPress site using the Autoptimize plugin. Because the injected scripts are stored and executed whenever any user accesses the affected page, this can lead to several security risks including session hijacking, defacement, unauthorized actions performed on behalf of users, or distribution of malware.

The impact is significant because the attack does not require user interaction (no user interface prompt) and affects all users who visit the compromised pages. The vulnerability exploits insufficient input sanitization and output escaping in the plugin's handling of preload link tags related to image optimization features.

The CVSS v3.1 base score of 6.4 (medium severity) reflects that the attack requires low complexity, privileges (Contributor or higher), no user interaction, and can lead to partial confidentiality and integrity loss but no availability impact.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "The vulnerability in the Autoptimize WordPress plugin (up to version 3.1.14) is a stored Cross-Site Scripting (XSS) issue via the 'ao_post_preload' meta value, exploitable by authenticated users with Contributor-level access or higher. Detection involves checking if your WordPress installation uses the Autoptimize plugin at or below version 3.1.14 and if the 'Image optimization' or 'Lazy-load images' settings are enabled."}, {'type': 'paragraph', 'content': "Since the vulnerability involves stored XSS via a meta value, detection on the system or network level can be challenging. However, you can audit the WordPress database for suspicious or unexpected script tags or payloads stored in post meta fields related to 'ao_post_preload'."}, {'type': 'paragraph', 'content': 'Suggested commands or steps include:'}, {'type': 'list_item', 'content': 'Use WP-CLI to search for suspicious content in post meta: `wp post meta list --post_id=<post_id> | grep ao_post_preload` and inspect values for injected scripts.'}, {'type': 'list_item', 'content': "Query the WordPress database directly to find meta values containing suspicious script tags: `SELECT post_id, meta_value FROM wp_postmeta WHERE meta_key = 'ao_post_preload' AND meta_value LIKE '%<script>%';`"}, {'type': 'list_item', 'content': 'Check the plugin version installed: `wp plugin get autoptimize --field=version` to verify if it is vulnerable (<= 3.1.14).'}, {'type': 'list_item', 'content': "Monitor HTTP responses for injected scripts in `<link>` tags related to preload resources, especially if the 'Image optimization' or 'Lazy-load images' features are enabled."}, {'type': 'paragraph', 'content': 'Note that no specific detection commands are provided in the resources, so these suggestions are based on understanding the vulnerability context and plugin behavior.'}] [1, 2, 3]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'The primary and immediate mitigation step is to update the Autoptimize WordPress plugin to version 3.1.15 or later, where the vulnerability has been fixed.'}, {'type': 'paragraph', 'content': 'Version 3.1.15 includes several security improvements addressing this vulnerability, such as sanitizing the \'ao_post_preload\' meta value input using `sanitize_text_field()`, sanitizing preload `<link>` tags with WordPress\'s `wp_kses()` function to allow only safe attributes, and adding the `fetchpriority="high"` attribute to preload links to improve resource loading security.'}, {'type': 'paragraph', 'content': 'Additional mitigation steps include:'}, {'type': 'list_item', 'content': 'Restrict Contributor-level and higher user permissions to trusted users only, as the vulnerability requires authenticated users with such access.'}, {'type': 'list_item', 'content': "Temporarily disable the 'Image optimization' and 'Lazy-load images' features in the Autoptimize plugin settings until the update can be applied."}, {'type': 'list_item', 'content': "Review and sanitize any existing 'ao_post_preload' meta values in the database to remove potentially malicious scripts."}, {'type': 'paragraph', 'content': 'Applying the official patch or update is the most effective and recommended action to fully mitigate the vulnerability.'}] [1, 2]

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Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-2352 is a Stored Cross-Site Scripting (XSS) vulnerability in the Autoptimize plugin for WordPress, affecting all versions up to and including 3.1.14. The vulnerability arises because the plugin does not properly sanitize input or escape output related to the \'ao_post_preload\' meta value. Specifically, the function `ao_metabox_save()` fails to sanitize user input, and the value is rendered without escaping into a <link> tag in the `autoptimizeImages.php` file. This allows authenticated users with Contributor-level access or higher to inject malicious scripts that execute whenever any user views the affected page, provided certain plugin settings like "Image optimization" or "Lazy-load images" are enabled.'}, {'type': 'paragraph', 'content': 'The vulnerability was addressed in version 3.1.15 by adding input sanitization using WordPress\'s `sanitize_text_field()` function on the meta box input, and by sanitizing the preload <link> tags with a whitelist of allowed HTML attributes using `wp_kses()`. Additional security improvements include adding the `fetchpriority="high"` attribute to preload links and securing HTML minification placeholders with cryptographically secure random values.'}] [1, 2]

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