CVE-2023-26537 in WP No External Links Plugin
Summary
by MITRE • 06/16/2023
Auth. (admin+) Stored Cross-Site Scripting (XSS) vulnerability in nicolly WP No External Links plugin <= 1.0.2 versions.
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Analysis
by VulDB Data Team • 07/14/2023
The CVE-2023-26537 vulnerability represents a critical stored cross-site scripting flaw within the nicolly WP No External Links plugin, affecting versions up to and including 1.0.2. This vulnerability specifically targets administrative users with privileges equal to or greater than administrator level, making it particularly dangerous in environments where plugin configurations are managed by privileged accounts. The issue stems from inadequate input validation and output sanitization mechanisms within the plugin's codebase, creating an opening for malicious actors to inject persistent malicious scripts into the plugin's administrative interface.
The technical implementation of this vulnerability occurs through the improper handling of user-supplied data within the plugin's configuration management system. When administrators interact with the plugin's settings or input fields, the application fails to properly sanitize or escape potentially malicious script content before storing it in the database. This stored data is then subsequently rendered in administrative interfaces without adequate security measures, allowing the injected scripts to execute within the context of other administrators' browsers. The vulnerability classifies under CWE-79 as a classic stored XSS attack vector, where malicious input is permanently stored and later executed, distinguishing it from reflected XSS attacks that require user interaction with malicious links.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to escalate privileges and potentially gain complete control over affected WordPress installations. Administrators who visit pages containing the stored malicious content become victims of the XSS attack, allowing attackers to steal session cookies, modify plugin configurations, or even redirect users to malicious sites. The attack surface is particularly concerning in enterprise environments where multiple administrators may interact with the plugin's interface, creating numerous potential entry points for persistent attacks. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1059.001 for command and scripting interpreter, and T1566 for phishing attacks that leverage web-based exploits.
Mitigation strategies for CVE-2023-26537 should prioritize immediate plugin updates to versions that address the XSS vulnerability, as the vendor has likely released patched versions. Organizations must also implement comprehensive input validation and output encoding measures throughout their WordPress environments, particularly focusing on administrative interfaces where privileged users interact with plugin configurations. Network-based security controls such as web application firewalls should be configured to detect and block suspicious script patterns in plugin-related requests. Additionally, implementing role-based access controls and regular security audits of installed plugins can help prevent unauthorized modifications that might introduce similar vulnerabilities. The vulnerability highlights the importance of maintaining current security practices and adhering to secure coding standards, particularly around input sanitization and output encoding, as specified in OWASP secure coding guidelines. Regular security assessments and penetration testing of administrative interfaces should be conducted to identify and remediate similar stored XSS vulnerabilities that may exist in other components of the WordPress ecosystem.