CVE-2025-39505: GoodLayers Hotel Plugin XSS Vulnerability

CVE-2025-39505 Overview

CVE-2025-39505 is a reflected Cross-Site Scripting (XSS) vulnerability in the GoodLayers Hotel (gdlr-hotel) WordPress plugin. The flaw stems from improper neutralization of user-supplied input during web page generation [CWE-79]. Attackers can craft malicious URLs containing JavaScript payloads that execute in a victim's browser when the link is clicked. All versions of Goodlayers Hotel up to and including 3.1.4 are affected. Successful exploitation allows session theft, credential harvesting, and unauthorized actions performed in the context of the authenticated victim.

Critical Impact

Reflected XSS enables attackers to execute arbitrary JavaScript in victims' browsers, leading to session hijacking, account takeover, and defacement of WordPress sites using vulnerable Goodlayers Hotel installations.

Affected Products

• GoodLayers Goodlayers Hotel plugin (gdlr-hotel) versions up to and including 3.1.4
• WordPress sites running the vulnerable plugin
• Hotel booking and reservation sites built on the Goodlayers Hotel theme ecosystem

Discovery Timeline

• 2025-05-23 - CVE-2025-39505 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-39505

Vulnerability Analysis

The Goodlayers Hotel plugin fails to properly sanitize and encode user-supplied input before reflecting it back in HTTP responses. An attacker constructs a URL containing JavaScript payloads in parameters processed by vulnerable endpoints in the plugin. When a victim clicks the crafted link, the server reflects the malicious input into the rendered HTML without encoding. The browser then executes the injected script in the context of the WordPress site's origin. This permits theft of session cookies, manipulation of page content, and execution of authenticated actions on behalf of the victim.

Root Cause

The root cause is missing output encoding and input sanitization on parameters consumed by the plugin's request handlers. The plugin does not apply WordPress functions such as esc_html(), esc_attr(), or sanitize_text_field() to data before echoing it back into the page response. This omission allows HTML and JavaScript syntax in attacker-controlled input to be interpreted as executable markup by the browser.

Attack Vector

Exploitation requires user interaction. The attack proceeds over the network and does not require authentication or prior privileges. An attacker delivers a crafted link via phishing email, malicious advertisement, or compromised third-party site. When an authenticated administrator or user clicks the link, the injected JavaScript executes within the site's security context. The scope change indicates the impact extends beyond the vulnerable component to other browser-trusted resources such as cookies for the parent WordPress domain.

No verified proof-of-concept code is publicly available. Refer to the Patchstack Vulnerability Report for additional technical context.

Detection Methods for CVE-2025-39505

Indicators of Compromise

• HTTP request logs containing URL parameters with <script>, javascript:, or HTML event handler strings (e.g., onerror=, onload=) directed at Goodlayers Hotel plugin endpoints
• Referrer headers from external domains pointing to unusual query strings on /wp-content/plugins/gdlr-hotel/ paths
• Outbound browser requests to attacker-controlled domains immediately after a user visits a crafted plugin URL
• WordPress administrator accounts performing unexpected actions shortly after clicking external links

Detection Strategies

• Deploy a Web Application Firewall (WAF) with rules that block reflected XSS patterns in query strings targeting WordPress plugins
• Inspect access logs for URL-encoded JavaScript payloads such as %3Cscript%3E or %3Cimg+src%3D parameters
• Use static analysis on the gdlr-hotel plugin source to identify reflection points missing escaping functions
• Correlate browser exceptions and Content Security Policy (CSP) violation reports with plugin request paths

Monitoring Recommendations

• Enable verbose HTTP request logging on WordPress sites running Goodlayers Hotel and forward logs to a centralized analytics platform
• Configure Content Security Policy headers with script-src restrictions and a reporting endpoint to surface injection attempts
• Alert on administrator session anomalies, including new IP addresses or geolocation changes shortly after URL clicks
• Monitor Patchstack and WordPress vulnerability feeds for updates and exploitation telemetry

How to Mitigate CVE-2025-39505

Immediate Actions Required

• Update the Goodlayers Hotel plugin to a version newer than 3.1.4 once the vendor releases a patched release
• Disable the gdlr-hotel plugin if a patched version is not yet available and the functionality is non-essential
• Audit administrator accounts for suspicious activity and rotate session cookies and credentials
• Educate site administrators to avoid clicking unsolicited links pointing to their own WordPress installation

Patch Information

Review the Patchstack Vulnerability Report for vendor remediation status. The advisory lists affected versions as n/a through <= 3.1.4. Apply any updates published by GoodLayers immediately and verify the plugin version after upgrade.

Workarounds

• Deploy WAF rules that filter requests containing HTML or JavaScript syntax in parameters destined for gdlr-hotel endpoints
• Implement a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins
• Restrict WordPress administration access by IP allowlist or VPN to reduce exposure to crafted phishing links
• Use browser-based XSS protections and require multi-factor authentication for all WordPress administrator accounts

# Example WAF rule (ModSecurity) to block reflected XSS payloads on gdlr-hotel paths
SecRule REQUEST_URI "@contains /wp-content/plugins/gdlr-hotel/" \
  "chain,id:1003950,phase:2,deny,status:403,msg:'Blocked XSS attempt on Goodlayers Hotel'"
  SecRule ARGS "@rx (?i)(<script|javascript:|onerror=|onload=)" \
    "t:none,t:urlDecodeUni"