CVE-2017-18536 in stop-user-enumeration Plugin
Summary
by MITRE
The stop-user-enumeration plugin before 1.3.8 for WordPress has XSS.
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Analysis
by VulDB Data Team • 01/23/2026
The CVE-2017-18536 vulnerability represents a cross-site scripting flaw within the stop-user-enumeration WordPress plugin, affecting versions prior to 1.3.8. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically manifesting as a reflected XSS attack vector that could be exploited by malicious actors to inject malicious scripts into web pages viewed by other users. The stop-user-enumeration plugin serves as a security enhancement designed to prevent user enumeration attacks by blocking direct access to user information through various WordPress endpoints, but the XSS flaw undermines its security posture and creates additional attack surface.
The technical implementation of this vulnerability occurs when the plugin fails to properly sanitize or escape user input before rendering it within web page responses. Attackers can craft malicious payloads that, when processed by the plugin, get executed in the context of other users' browsers. This typically involves injecting script tags or other malicious code through parameters that are not adequately validated or escaped. The vulnerability is particularly concerning because it exists within a security plugin that is specifically designed to protect against enumeration attacks, creating a paradoxical situation where the security tool itself becomes a vector for exploitation.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious sites. When users with administrative privileges access pages that trigger the vulnerable code path, the attacker gains elevated privileges to compromise the entire WordPress installation. The vulnerability aligns with ATT&CK technique T1566.002 for initial access through spearphishing attachments, as attackers could leverage the XSS to deliver additional payloads or redirect users to malicious sites that harvest credentials. The attack chain typically involves the attacker crafting a malicious URL or form submission that when processed by the vulnerable plugin, executes the attacker's script in the victim's browser context.
Mitigation strategies for CVE-2017-18536 primarily focus on immediate plugin updates to version 1.3.8 or later, which contain the necessary code sanitization and input validation fixes. Administrators should also implement additional security measures including web application firewalls, input validation at multiple layers, and regular security auditing of installed plugins. The vulnerability demonstrates the critical importance of proper output encoding and input validation in security plugins, as these tools often handle sensitive user data and must themselves be protected against common web vulnerabilities. Organizations should also consider implementing Content Security Policy headers and regular security scanning to detect similar issues in other plugins or custom code implementations. The incident highlights the necessity of maintaining up-to-date security tools and following secure coding practices that prevent XSS vulnerabilities from being introduced into security-focused applications.