CVE-2025-9849 in Html Social Share Buttons Plugin
Summary
by MITRE • 09/06/2025
The Html Social share buttons plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'zm_sh_btn' shortcode in all versions up to, and including, 2.1.16 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 09/06/2025
The Html Social share buttons plugin for WordPress presents a critical stored cross-site scripting vulnerability identified as CVE-2025-9849 affecting versions up to and including 2.1.16. This vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's zm_sh_btn shortcode implementation, creating a persistent security flaw that can be exploited by authenticated attackers possessing contributor-level privileges or higher. The vulnerability operates by allowing malicious actors to inject malicious scripts through user-supplied attributes that are not properly validated or escaped before being rendered in web pages.
The technical flaw manifests in the plugin's failure to adequately sanitize user input parameters passed to the zm_sh_btn shortcode, specifically targeting attributes that control the display and functionality of social sharing buttons. When these attributes contain malicious script content, the plugin processes them without sufficient validation, storing the malicious code within the WordPress database. This stored payload executes whenever any user accesses a page containing the vulnerable shortcode, making it a persistent threat that affects all visitors regardless of their privilege level. The vulnerability directly maps to CWE-79, which defines Cross-Site Scripting (XSS) as the improper handling of input data that enables attackers to inject client-side scripts into web applications.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the capability to perform various malicious activities including session hijacking, credential theft, and redirection to malicious websites. An authenticated attacker with contributor privileges can craft malicious shortcodes that, when embedded in posts or pages, will execute scripts in the context of other users' browsers. This creates a significant risk for WordPress sites where contributors might have access to publish content, as they can effectively compromise the entire user base by injecting malicious code that executes whenever legitimate users view affected pages. The attack vector is particularly concerning because it requires minimal privileges and can be executed through standard content creation workflows.
Mitigation strategies for CVE-2025-9849 should prioritize immediate plugin updates to versions that address the sanitization and escaping deficiencies. Administrators must implement comprehensive input validation for all user-supplied attributes within the zm_sh_btn shortcode and ensure that output escaping is properly applied before rendering any dynamic content. The implementation of Content Security Policy headers can provide additional defense-in-depth measures by restricting script execution within the affected WordPress environment. Regular security audits should be conducted to identify similar vulnerabilities in other plugins and themes, as this type of flaw often indicates broader sanitization issues within the WordPress ecosystem. Organizations should also consider implementing privileged access controls and monitoring for suspicious shortcode usage patterns, particularly in environments where multiple users have contributor-level access or higher, aligning with ATT&CK technique T1078 for valid accounts and T1546 for privilege escalation through content injection.