CVE-2026-39654 in WP Simple HTML Sitemap Plugin
Summary
by MITRE • 04/08/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Ashish Ajani WP Simple HTML Sitemap wp-simple-html-sitemap allows DOM-Based XSS.This issue affects WP Simple HTML Sitemap: from n/a through <= 3.8.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/08/2026
This vulnerability represents a classic cross-site scripting flaw that specifically targets the wp-simple-html-sitemap plugin for WordPress. The issue manifests as a DOM-based XSS attack, where malicious input is improperly handled during the generation of web pages, allowing attackers to inject malicious scripts into the browser's document object model. The vulnerability exists within the plugin's input processing mechanisms, where user-supplied data fails to undergo proper sanitization before being rendered in HTML output contexts. This particular weakness enables attackers to execute arbitrary JavaScript code within the victim's browser session, potentially leading to session hijacking, credential theft, or other malicious activities.
The technical flaw resides in the plugin's failure to properly neutralize input parameters during web page generation processes. When the wp-simple-html-sitemap plugin processes user requests or parameters, it does not adequately validate or escape data that gets incorporated into dynamically generated HTML content. This improper handling creates an environment where malicious scripts can be injected and executed within the browser context of legitimate users who visit affected pages. The vulnerability specifically impacts versions of the plugin ranging from the initial release through version 3.8, indicating a long-standing issue that has not been properly addressed in the codebase.
The operational impact of this vulnerability extends beyond simple script execution, as it can be exploited to perform sophisticated attacks against authenticated users. Attackers can craft malicious URLs or input parameters that, when processed by the vulnerable plugin, result in script injection within the DOM. This allows for persistent XSS attacks where malicious code can be stored and executed whenever affected pages are accessed. The vulnerability is particularly concerning in WordPress environments where administrators or users with elevated privileges may be targeted, as successful exploitation could lead to complete compromise of affected sites. Additionally, the DOM-based nature of the vulnerability means that traditional server-side input validation may not prevent exploitation, making detection and mitigation more challenging.
Security mitigations for this vulnerability should focus on immediate patching of the affected plugin to version 3.9 or later, where the XSS flaws have been addressed through proper input sanitization and output encoding. Organizations should implement comprehensive input validation mechanisms that ensure all user-supplied data is properly escaped before being incorporated into HTML content. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent script execution, while regular security auditing of WordPress plugins should be conducted to identify similar vulnerabilities. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1566.001 for initial access through malicious web content, highlighting the need for both preventive and detective security controls.