CVE-2021-24859 in User Meta Shortcodes Plugin
Summary
by MITRE • 12/13/2021
The User Meta Shortcodes WordPress plugin through 0.5 registers a shortcode that allows any user with a role as low as contributor to access other users metadata by specifying the user login as a parameter. This makes the WP instance vulnerable to data extrafiltration, including password hashes
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Analysis
by VulDB Data Team • 12/15/2021
The vulnerability identified as CVE-2021-24859 affects the User Meta Shortcodes WordPress plugin version 0.5 and earlier, presenting a significant security flaw that undermines user privacy and system integrity. This issue stems from improper access control mechanisms within the plugin's shortcode implementation, which fails to adequately verify user permissions before exposing sensitive metadata. The vulnerability specifically targets the plugin's ability to register shortcodes that can be invoked by contributors, a role that typically should not possess access to other users' metadata. The flaw allows unauthorized data extraction through parameter manipulation, where a contributor can specify any user login to retrieve comprehensive metadata associated with that account.
The technical implementation of this vulnerability resides in the plugin's insufficient input validation and access control checks. When a shortcode is registered, the plugin does not properly authenticate or authorize the requesting user's role before executing the metadata retrieval function. This design flaw creates an information disclosure vulnerability that operates at the application level, allowing attackers to enumerate user accounts and extract sensitive information including password hashes that are typically stored in WordPress databases. The vulnerability is classified under CWE-284, which addresses improper access control, and represents a direct violation of the principle of least privilege that should govern all user interactions within WordPress systems.
The operational impact of CVE-2021-24859 extends beyond simple information disclosure, as it provides attackers with the capability to perform reconnaissance activities that could lead to more severe compromises. By accessing other users' metadata, including password hashes, attackers can potentially conduct credential stuffing attacks or target specific users for social engineering operations. The vulnerability affects any WordPress instance running the affected plugin version, regardless of the hosting environment or additional security measures implemented. This weakness creates a persistent threat vector that remains active until the plugin is updated or the vulnerable shortcode functionality is disabled, making it particularly concerning for multi-user environments where contributor-level access is common.
Mitigation strategies for this vulnerability should focus on immediate remediation through plugin updates to version 0.5.1 or later, which contains the necessary access control fixes. System administrators should also implement additional monitoring to detect unauthorized shortcode usage patterns and consider disabling the specific shortcode functionality if it is not essential for operations. The vulnerability aligns with ATT&CK technique T1078.004, which covers legitimate credentials, as attackers can exploit this weakness to obtain password hashes and other credential-related information. Organizations should also conduct comprehensive audits of all installed plugins to identify similar access control vulnerabilities and ensure proper role-based access controls are enforced throughout their WordPress environments. Regular security assessments and vulnerability scanning should be implemented to detect similar issues that may exist in other third-party components that could potentially expose user metadata or system information.