Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-2687 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin "Reading progressbar" versions before 1.3.1.'}, {'type': 'paragraph', 'content': 'The vulnerability occurs because the plugin does not properly sanitize and escape certain settings fields, such as "Progressbar height (pixels)" and "Target fixed HTML element class/id to stick the bar on its bottom."'}, {'type': 'paragraph', 'content': 'This flaw allows users with high privileges, like administrators, to inject malicious scripts that are stored in the plugin settings and executed later in the admin interface, even if the unfiltered_html capability is disabled (for example, in multisite WordPress setups).'}, {'type': 'paragraph', 'content': 'The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation) and corresponds to OWASP Top 10 category A7: Cross-Site Scripting (XSS).'}] [1]

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Impact Analysis

This vulnerability allows high privilege users, such as administrators, to perform Stored Cross-Site Scripting attacks by injecting malicious JavaScript into plugin settings.

The malicious scripts are executed in the context of the admin interface, which could lead to unauthorized actions, session hijacking, or other malicious activities within the WordPress admin environment.

Even if the unfiltered_html capability is disabled, the vulnerability still allows script injection, increasing the risk in multisite WordPress setups.

The CVSS v3.1 base score is 3.5, indicating a low severity level, but the impact depends on the privileges of the attacker and the environment.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by checking the settings of the Reading progressbar WordPress plugin for malicious script injections in specific fields.'}, {'type': 'paragraph', 'content': 'Specifically, inspect the "Progressbar height (pixels)" and "Target fixed HTML element class/id to stick the bar on its bottom" fields for suspicious content such as JavaScript payloads.'}, {'type': 'paragraph', 'content': "A proof of concept payload to look for is: ' style='animation-name:rotation' onanimationstart='alert(/XSS/)//"}, {'type': 'paragraph', 'content': 'You can detect this by querying the WordPress database directly, for example using SQL commands to search the wp_options table (or wherever the plugin stores its settings) for suspicious script content.'}, {'type': 'list_item', 'content': "Example SQL command to find suspicious entries: SELECT option_name, option_value FROM wp_options WHERE option_value LIKE '%onanimationstart=%';"}, {'type': 'list_item', 'content': 'Alternatively, use WP-CLI to get plugin settings and manually inspect them.'}] [1]

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Mitigation Strategies

The immediate step to mitigate this vulnerability is to update the Reading progressbar WordPress plugin to version 1.3.1 or later, where the issue has been fixed.

Until the update is applied, restrict high privilege user access to the plugin settings to prevent exploitation.

Additionally, review and sanitize any existing plugin settings to remove malicious scripts.

Consider implementing additional security measures such as a Web Application Firewall (WAF) to block malicious payloads.

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