CVE-2026-13701 in Advanced Excerpt Plugin
Summary
by MITRE • 08/10/2026
The Advanced Excerpt WordPress plugin before 4.5 does not sanitise and escape one of its settings before outputting it on the front end of the site, which could allow administrators (including those without the unfiltered_html capability, such as on multisite) to perform Stored Cross-Site Scripting attacks that execute in the context of any visitor viewing affected pages.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in the Advanced Excerpt WordPress plugin prior to version 4.5 represents a critical stored cross-site scripting flaw that exploits insufficient input validation and output sanitization mechanisms within the plugin's settings handling process. This weakness allows authenticated attackers with administrator privileges to inject malicious scripts into plugin configurations that are subsequently executed when visitors access affected pages. The vulnerability is particularly concerning because it can be exploited by users who lack the unfiltered_html capability, which typically grants unrestricted HTML insertion permissions in WordPress environments, making it accessible to a broader range of potential attackers within multisite installations where privilege levels may be more restrictive.
The technical implementation of this vulnerability stems from the plugin's failure to properly sanitize and escape user-provided input before rendering it on the front-end display. When administrators configure certain plugin settings through the WordPress admin interface, the data is stored without adequate validation or escaping mechanisms that would prevent malicious script execution. This allows attackers to inject javascript code or other malicious payloads into configuration fields that are then output directly to web pages without proper HTML entity encoding or context-appropriate sanitization. The flaw exists in the plugin's template rendering logic where user-controllable settings are embedded directly into page content without appropriate security measures, creating an environment where any visitor who views affected pages becomes a potential victim of the stored script execution.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to execute arbitrary scripts in the context of any visitor's browser session. This means that malicious actors can potentially steal cookies, session tokens, or other sensitive information from users who visit pages affected by the vulnerability. The attack vector is particularly dangerous because it requires minimal privileges to exploit and can affect any user who visits vulnerable pages, making it a scalable threat for website administrators. In multisite environments, this vulnerability becomes even more concerning as attackers may gain access to multiple sites through compromised administrator accounts, potentially leading to widespread compromise across networked WordPress installations.
Mitigation strategies for this vulnerability should focus on immediate plugin updates to version 4.5 or later where the sanitization issues have been addressed. Administrators should also implement additional security measures such as regular security audits of plugin configurations and monitoring for unauthorized changes to plugin settings. The implementation of content security policies can provide additional protection layers against script execution, while regular backups ensure rapid recovery from potential compromise scenarios. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and represents a clear violation of secure coding practices that should be enforced through proper input validation and output encoding mechanisms. From an ATT&CK framework perspective, this vulnerability maps to techniques involving code injection and privilege escalation within web application contexts, emphasizing the importance of maintaining up-to-date software and implementing robust access controls for administrative functions.