CVE-2023-3746 in ActivityPub Plugin
Summary
by MITRE • 10/25/2023
The ActivityPub WordPress plugin before 1.0.0 does not sanitize and escape some data from post content, which could allow contributor and above role to perform Stored Cross-Site Scripting attacks
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/10/2026
The ActivityPub WordPress plugin vulnerability represents a critical security flaw that affects versions prior to 1.0.0, specifically targeting users with contributor roles and higher. This vulnerability stems from insufficient data sanitization and escaping mechanisms within the plugin's handling of post content, creating an avenue for stored cross-site scripting attacks that can compromise user sessions and execute malicious code within the context of affected websites. The flaw operates at the application layer and directly impacts the plugin's ability to properly validate and sanitize user input, particularly when processing content that should be treated as potentially dangerous.
The technical implementation of this vulnerability occurs when users with contributor privileges or higher create or modify posts containing malicious script code within the content. The plugin fails to properly sanitize this input before storing it in the database, and subsequently fails to escape the data when rendering it in web pages. This dual failure creates a persistent XSS vector where the malicious code is stored and then executed whenever the affected content is displayed to other users. The vulnerability specifically targets the plugin's handling of post content, which is processed through ActivityPub's federation mechanisms, making it particularly dangerous in multi-user environments where content is shared across different platforms.
The operational impact of this vulnerability extends beyond simple script execution, as it allows attackers with contributor-level access to potentially escalate their privileges, steal user sessions, redirect visitors to malicious sites, or extract sensitive information from the WordPress installation. The stored nature of the vulnerability means that the malicious payload persists even after the initial injection, making it particularly dangerous as it can affect any user who views the compromised content. This vulnerability directly maps to CWE-79 which defines Cross-Site Scripting as a common weakness in web applications where untrusted data is improperly handled. The attack vector follows typical XSS exploitation patterns and can be classified under ATT&CK technique T1059.007 for command and scripting interpreter, specifically focusing on script injection techniques.
Mitigation strategies should focus on immediate plugin updates to version 1.0.0 or later, which contains the necessary sanitization and escaping fixes. Administrators should also implement additional security measures including role-based access control reviews, content filtering mechanisms, and regular security audits of installed plugins. The WordPress security team recommends that all users immediately update their ActivityPub plugin installations and conduct thorough security assessments of their WordPress environments. Organizations should also consider implementing web application firewalls and content security policies to provide additional layers of protection against similar vulnerabilities in other plugins or themes. Regular monitoring of plugin repositories and security advisories remains essential for maintaining secure WordPress installations and preventing exploitation of similar weaknesses in the broader WordPress ecosystem.