CVE-2024-0561 in Ultimate Posts Widget Plugin
Summary
by MITRE • 03/11/2024
The Ultimate Posts Widget WordPress plugin before 2.3.1 does not validate and escape some of its Widget options before outputting them back in attributes, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)
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Analysis
by VulDB Data Team • 04/16/2025
The vulnerability identified as CVE-2024-0561 affects the Ultimate Posts Widget WordPress plugin version 2.3.0 and earlier, presenting a critical security risk through stored cross-site scripting flaws. This issue arises from insufficient input validation and output escaping mechanisms within the plugin's widget options handling process. The flaw specifically targets the plugin's inability to properly sanitize user-provided data before rendering it as HTML attributes, creating an environment where malicious scripts can be persistently stored and executed within the WordPress administration interface.
The technical implementation of this vulnerability stems from the plugin's failure to apply proper sanitization routines to widget configuration parameters. When administrators or other high-privilege users configure the widget options through the WordPress admin dashboard, the plugin stores these values without adequate validation or escaping. This weakness becomes particularly dangerous when combined with WordPress's capability management system, where even users with restricted permissions might be able to inject malicious payloads that persist across sessions. The vulnerability is especially concerning in multisite environments where the unfiltered_html capability is typically restricted for security reasons.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with persistent access to administrative interfaces through stored XSS vectors. An attacker with access to a high-privilege account can inject malicious JavaScript code into widget options that will execute whenever the widget is rendered or when administrators view the widget configuration pages. This creates a persistent threat that can be used to escalate privileges, steal session cookies, modify content, or redirect users to malicious sites. The vulnerability is particularly dangerous because it operates within the WordPress admin environment where attackers can gain access to sensitive administrative functions and data.
Mitigation strategies for this vulnerability require immediate plugin updates to version 2.3.1 or later, which contain the necessary sanitization fixes. System administrators should also implement additional security measures including regular security audits of installed plugins, monitoring for unauthorized configuration changes, and ensuring that only necessary users have administrative privileges. The vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and maps to ATT&CK technique T1548.002 for privilege escalation through exploitation of administrative interfaces. Organizations should also consider implementing Content Security Policy headers and regular automated vulnerability scanning to detect similar issues in other plugins or themes that might not have been properly patched.