CVE-2021-36889 in Cookies legislation & GDPR Plugin
Summary
by MITRE • 12/21/2021
Multiple Stored Authenticated Cross-Site Scripting (XSS) vulnerabilities were discovered in tarteaucitron.js – Cookies legislation & GDPR WordPress plugin (versions
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Analysis
by VulDB Data Team • 12/25/2021
The vulnerability CVE-2021-36889 represents a critical stored authenticated cross-site scripting flaw within the tarteaucitron.js WordPress plugin, which is widely used for managing cookie consent and GDPR compliance. This plugin serves as a crucial tool for websites to handle cookie policies and user consent tracking, making it a prime target for attackers seeking to exploit user sessions and gather sensitive information. The vulnerability affects multiple versions of the tarteaucitron.js plugin, creating a widespread security risk across numerous WordPress installations that rely on this cookie management solution for regulatory compliance. The flaw specifically resides in how the plugin handles user input within its configuration interfaces, where unfiltered data is stored and subsequently executed in the browser context of authenticated users.
The technical implementation of this vulnerability stems from inadequate input validation and output escaping mechanisms within the plugin's administrative interfaces. When administrators or authorized users modify cookie settings through the WordPress dashboard, the plugin fails to properly sanitize the input data before storing it in the database. This stored data is then retrieved and rendered without proper HTML escaping, creating an environment where malicious scripts can be injected and executed whenever the affected pages are loaded. The vulnerability is classified as authenticated because it requires users to have administrative privileges or other elevated permissions within the WordPress environment, but once exploited, it allows attackers to execute arbitrary JavaScript code in the context of the victim's browser session. This type of vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws, and aligns with ATT&CK technique T1566.002 for Phishing with Malicious Attachments and T1059.001 for Command and Scripting Interpreter.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and privilege escalation within the WordPress environment. An attacker who gains access to an administrative account can leverage this vulnerability to inject persistent malicious scripts that will execute whenever any administrator visits the affected pages. This capability allows for long-term persistence and can be used to establish covert channels for data theft, modify plugin configurations, or even redirect users to malicious websites. The stored nature of the vulnerability means that the malicious code remains active even after the initial injection, making it particularly dangerous for maintaining prolonged access to compromised systems. The impact is further amplified by the fact that many WordPress administrators may not regularly audit their plugin configurations, allowing the malicious scripts to remain undetected for extended periods.
Mitigation strategies for CVE-2021-36889 should prioritize immediate plugin updates to versions that have addressed the input sanitization issues and implemented proper output escaping mechanisms. Organizations should also implement network-based monitoring to detect anomalous script loading patterns and unauthorized modifications to plugin configurations. The WordPress security community recommends conducting comprehensive audits of all plugin installations to identify potentially vulnerable versions and ensure that proper input validation is in place. Additional defensive measures include implementing Content Security Policy headers to limit script execution, regularly backing up plugin configurations, and maintaining detailed logs of administrative activities. Organizations should also consider implementing privileged access management solutions and multi-factor authentication to reduce the risk of unauthorized access to administrative accounts, as the vulnerability requires elevated privileges to exploit but can have devastating consequences once successful. Regular security assessments and vulnerability scanning should be performed to identify similar issues in other plugins and ensure that all WordPress components maintain proper security hygiene throughout the application lifecycle.