CVE-2025-27309 Overview
CVE-2025-27309 is a stored cross-site scripting (XSS) vulnerability in the Jeannot Muller flickr-slideshow-wrapper WordPress plugin. The flaw affects all versions up to and including 5.4.6. Attackers can inject malicious scripts that persist in the application and execute in the browsers of users who view affected pages. The vulnerability is classified under CWE-79, Improper Neutralization of Input During Web Page Generation.
Exploitation occurs over the network and requires user interaction, with a scope change that allows the injected payload to affect resources beyond the vulnerable component.
Critical Impact
Stored XSS in the flickr-slideshow-wrapper plugin allows attackers to execute arbitrary JavaScript in victim browsers, enabling session hijacking, credential theft, and unauthorized actions on behalf of authenticated WordPress users.
Affected Products
- Jeannot Muller flickr-slideshow-wrapper WordPress plugin
- All versions from initial release through 5.4.6
- WordPress sites with the plugin installed and active
Discovery Timeline
- 2025-04-17 - CVE-2025-27309 published to NVD
- 2026-04-23 - Last updated in NVD database
Technical Details for CVE-2025-27309
Vulnerability Analysis
The vulnerability stems from improper neutralization of user-supplied input within the flickr-slideshow-wrapper plugin. The plugin fails to sanitize or encode input before storing it and later rendering it within generated web pages. An attacker with the ability to submit content through the plugin's input handlers can inject HTML or JavaScript that is persistently saved to the database.
When a legitimate user loads a page that renders the stored content, the browser parses and executes the attacker-controlled script in the context of the WordPress site. This enables session hijacking, theft of authentication cookies, redirection to attacker-controlled sites, and arbitrary actions performed under the victim's privileges.
The scope-changing nature of the flaw means the impact extends beyond the plugin itself, affecting any user or component that consumes the compromised output within the WordPress site.
Root Cause
The root cause is missing or insufficient output encoding and input validation within the plugin's data handling routines. User input is accepted, stored, and later echoed into the HTML response without being escaped through WordPress sanitization functions such as esc_html(), esc_attr(), or wp_kses().
Attack Vector
An attacker submits a crafted payload containing JavaScript or HTML markup to a plugin input field. The payload is persisted in the WordPress database. When a visitor or administrator loads a page rendering the stored value, the malicious script executes in their browser session. The attack requires user interaction in the form of visiting an affected page.
No proof-of-concept code is publicly available. Refer to the Patchstack WordPress Vulnerability Report for additional technical context.
Detection Methods for CVE-2025-27309
Indicators of Compromise
- Unexpected <script>, <iframe>, or event handler attributes (e.g., onerror, onload) stored within wp_postmeta or plugin-specific database tables
- Outbound HTTP requests from visitor browsers to unfamiliar domains following page loads on pages using the slideshow plugin
- Unauthorized administrative actions or new privileged accounts created shortly after content updates involving the plugin
Detection Strategies
- Review WordPress database tables for stored content containing HTML or JavaScript tags submitted through flickr-slideshow-wrapper fields
- Inspect rendered HTML output of pages embedding the plugin for unescaped angle brackets, inline event handlers, or remote script references
- Correlate web server access logs with POST requests targeting plugin endpoints to identify injection attempts
Monitoring Recommendations
- Enable Content Security Policy (CSP) reporting to surface inline script execution and unauthorized resource loads
- Monitor administrator and editor session activity for anomalous behavior such as unexpected profile edits or plugin installations
- Audit plugin update status and version inventory across WordPress instances on a recurring schedule
How to Mitigate CVE-2025-27309
Immediate Actions Required
- Deactivate the flickr-slideshow-wrapper plugin until a patched version is confirmed available and installed
- Audit all content rendered by the plugin and remove any suspicious HTML or JavaScript stored in the database
- Rotate WordPress administrator credentials and invalidate active sessions if exploitation is suspected
Patch Information
At the time of publication, the Patchstack advisory identifies all versions through 5.4.6 as vulnerable. Site operators should monitor the WordPress plugin repository for an updated release and apply it as soon as it becomes available.
Workarounds
- Remove the flickr-slideshow-wrapper plugin entirely if Flickr slideshow functionality is not required
- Deploy a web application firewall (WAF) with rules to block XSS payloads targeting plugin input parameters
- Restrict plugin configuration access to trusted administrators only and enforce least-privilege role assignments
- Implement a strict Content Security Policy that disallows inline scripts and untrusted script sources
# Configuration example: deactivate plugin via WP-CLI
wp plugin deactivate flickr-slideshow-wrapper
wp plugin uninstall flickr-slideshow-wrapper
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
