CVE-2017-6817 in WordPress
Summary
by MITRE
In WordPress before 4.7.3 (wp-includes/embed.php), there is authenticated Cross-Site Scripting (XSS) in YouTube URL Embeds.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2017-6817 represents a critical authenticated cross-site scripting flaw affecting WordPress installations prior to version 4.7.3. This security issue specifically resides within the wp-includes/embed.php file and manifests when processing YouTube URL embeds, making it particularly dangerous for content management systems that rely heavily on multimedia integration. The flaw allows authenticated users with sufficient privileges to inject malicious scripts into embedded YouTube content, potentially compromising the security of entire WordPress installations.
The technical nature of this vulnerability stems from insufficient input validation and output escaping mechanisms within WordPress's embed processing functionality. When administrators or users with appropriate permissions create posts containing YouTube URLs, the system fails to properly sanitize the embedded content before rendering it in web browsers. This inadequate sanitization creates an opening for attackers to execute malicious JavaScript code through carefully crafted YouTube URLs that contain malicious payloads. The vulnerability operates under CWE-79 which specifically addresses Cross-Site Scripting flaws, and aligns with ATT&CK technique T1203 which involves exploiting web application vulnerabilities to execute arbitrary code.
The operational impact of CVE-2017-6817 extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, data theft, and privilege escalation within the WordPress environment. An authenticated attacker with contributor or higher privileges can leverage this vulnerability to inject persistent scripts that execute whenever the embedded content is viewed, potentially affecting all users who access the compromised content. This makes the vulnerability particularly dangerous in multi-user environments where administrators may unknowingly embed malicious content or where attackers have gained access to accounts with sufficient permissions.
Mitigation strategies for this vulnerability primarily involve upgrading to WordPress version 4.7.3 or later, which includes proper input sanitization and output escaping mechanisms for embedded content. Organizations should also implement additional security measures such as regular security audits, input validation policies, and monitoring of user activities within WordPress installations. The fix addresses the core issue by implementing proper HTML entity encoding and input validation for YouTube URLs, preventing malicious scripts from being executed in the browser context. Security teams should also consider implementing web application firewalls and content security policies as additional protective layers against similar vulnerabilities in the future.