CVE-2026-33559 Overview
A cross-site scripting (XSS) vulnerability has been identified in the WordPress Plugin "OpenStreetMap" provided by MiKa. On sites with the affected version of the plugin enabled, a logged-in user with page-creating or editing privileges can embed malicious scripts through a crafted HTTP request. When a victim user accesses the compromised page, the script may be executed in the user's web browser, potentially leading to session hijacking, credential theft, or other malicious actions.
Critical Impact
Authenticated users with content editing privileges can inject malicious JavaScript that executes in the browsers of other users who view the affected page, enabling potential session hijacking and data theft.
Affected Products
- WordPress Plugin "OpenStreetMap" by MiKa (affected versions not specified)
- WordPress installations with the OSM plugin enabled
Discovery Timeline
- 2026-03-27 - CVE-2026-33559 published to NVD
- 2026-03-30 - Last updated in NVD database
Technical Details for CVE-2026-33559
Vulnerability Analysis
This vulnerability is classified as a stored cross-site scripting (XSS) flaw (CWE-79: Improper Neutralization of Input During Web Page Generation). The plugin fails to properly sanitize user-supplied input when processing HTTP requests related to map content or configuration. Because the malicious payload is stored on the server and served to subsequent visitors, this constitutes a persistent XSS attack rather than a reflected one.
The attack requires the attacker to have authenticated access with page creation or editing privileges, which represents a common access level for WordPress content contributors and editors. Once the malicious script is embedded, it executes in the security context of visiting users' browsers, potentially exposing session tokens, cookies, and other sensitive data.
Root Cause
The root cause of this vulnerability lies in insufficient input validation and output encoding within the OpenStreetMap plugin. When processing HTTP requests that involve user-controlled data for map embedding or configuration, the plugin fails to properly sanitize or escape special characters before rendering them in the page output. This allows attackers to inject arbitrary JavaScript code that the browser interprets as legitimate page content.
Attack Vector
The attack is network-accessible and requires low complexity to execute. An attacker must first authenticate to the WordPress site with privileges to create or edit pages. The attacker then crafts a malicious HTTP request containing JavaScript payloads, typically embedded within map configuration parameters or shortcode attributes. When the page is saved and subsequently accessed by other users (including administrators), the malicious script executes within their browser session.
The stored nature of this XSS makes it particularly dangerous, as the payload persists and affects all users who view the compromised page. Potential attack outcomes include:
- Session token theft enabling account takeover
- Keylogging of sensitive information entered on the page
- Redirection to phishing sites
- Administrative action execution if an admin views the page
Detection Methods for CVE-2026-33559
Indicators of Compromise
- Unexpected JavaScript code within page content or post metadata related to OpenStreetMap shortcodes
- Unusual HTTP requests to the WordPress admin interface containing encoded script tags or JavaScript event handlers
- Browser console errors or unexpected script execution warnings when viewing pages with embedded maps
- User reports of unexpected behavior or redirects when accessing map-enabled pages
Detection Strategies
- Review page source and database content for suspicious JavaScript within OSM-related shortcodes or configuration
- Monitor WordPress activity logs for unauthorized page modifications by users with editing privileges
- Implement Content Security Policy (CSP) headers to detect and block inline script execution
- Utilize web application firewall (WAF) rules to identify XSS payload patterns in HTTP requests
Monitoring Recommendations
- Enable comprehensive logging for WordPress page creation and editing activities
- Deploy real-time monitoring for JavaScript injection patterns in submitted content
- Configure browser-based XSS auditors and security extensions for administrative users
- Regularly audit pages containing OpenStreetMap embeds for unauthorized modifications
How to Mitigate CVE-2026-33559
Immediate Actions Required
- Review all pages using the OpenStreetMap plugin for suspicious embedded scripts
- Temporarily disable the OpenStreetMap plugin until a patched version is available
- Audit user accounts with page editing privileges to ensure no compromised accounts exist
- Implement Content Security Policy headers to mitigate XSS impact
Patch Information
Users should monitor the WordPress Plugin Information page for updated versions that address this vulnerability. Additionally, the JVN Vulnerability Report provides official advisory information regarding remediation steps.
Workarounds
- Disable the OpenStreetMap plugin until an official patch is released
- Restrict page editing privileges to only trusted administrators
- Implement a Web Application Firewall (WAF) with XSS filtering rules
- Enable Content Security Policy (CSP) headers to prevent inline script execution
- Regularly backup and review page content for unauthorized modifications
# Example: Add Content Security Policy header in .htaccess
# This helps mitigate XSS by restricting script sources
Header set Content-Security-Policy "script-src 'self' https://unpkg.com https://cdn.jsdelivr.net; object-src 'none';"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
