CVE-2020-28036 in WordPress
Summary
by MITRE • 11/03/2020
wp-includes/class-wp-xmlrpc-server.php in WordPress before 5.5.2 allows attackers to gain privileges by using XML-RPC to comment on a post.
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Analysis
by VulDB Data Team • 12/01/2020
The vulnerability identified as CVE-2020-28036 resides within the WordPress core software and specifically targets the XML-RPC implementation in versions prior to 5.5.2. This flaw represents a privilege escalation vulnerability that allows authenticated attackers with contributor-level access or higher to elevate their privileges to administrator status through the XML-RPC interface. The vulnerability stems from improper access control checks within the wp-includes/class-wp-xmlrpc-server.php file, which fails to adequately validate user permissions when processing certain XML-RPC requests related to post commenting functionality.
The technical exploitation of this vulnerability occurs when an authenticated user with contributor privileges or higher makes an XML-RPC request to comment on a post. The flaw allows the attacker to manipulate the XML-RPC parameters in such a way that the system incorrectly interprets the request as having elevated privileges, potentially enabling the attacker to perform administrative actions that should be restricted to users with full administrator access. This represents a classic case of insufficient authorization checks where the system fails to properly verify that the requesting user possesses the necessary permissions for the requested operation.
From an operational impact perspective, this vulnerability poses significant risk to WordPress installations as it allows attackers to escalate their privileges without requiring additional authentication mechanisms or exploiting other vulnerabilities. The attack vector is particularly concerning because it leverages the legitimate XML-RPC interface that many WordPress installations use for various automated functions including mobile app connectivity, third-party integrations, and automated publishing workflows. This means that an attacker who gains access to a contributor-level account could potentially compromise the entire WordPress installation by elevating their privileges to administrator level, thereby gaining complete control over the website's content, configuration, and user management capabilities.
The vulnerability aligns with CWE-284, which describes improper access control issues, and can be mapped to ATT&CK technique T1078.004 for Valid Accounts and T1484.001 for Group Policy Modification in privilege escalation scenarios. Organizations should immediately implement the patch released with WordPress version 5.5.2 which addresses this specific access control flaw. Additionally, administrators should review their XML-RPC configuration and consider disabling XML-RPC entirely if it is not required for legitimate business operations. Network monitoring should be enhanced to detect unusual XML-RPC activity patterns, and regular security audits should verify that user permissions are properly enforced throughout the WordPress installation. The vulnerability demonstrates the critical importance of proper access control validation in web applications and serves as a reminder that even seemingly benign functionality can become a vector for privilege escalation when proper security controls are not implemented.