CVE-2025-9849 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Html Social share buttons plugin for WordPress, developed by alimuzzamanalim. This vulnerability affects all versions up to and including 2.1.16. The root cause is insufficient input sanitization and output escaping on user-supplied attributes within the plugin's 'zm_sh_btn' shortcode. Authenticated attackers with contributor-level access or higher can exploit this flaw by injecting arbitrary JavaScript code into pages where the shortcode is used. When other users visit these compromised pages, the malicious scripts execute in their browsers. This type of stored XSS can lead to session hijacking, defacement, or redirection to malicious sites. The CVSS v3.1 base score is 5.3, indicating a medium severity level. The attack vector is network-based with low attack complexity and no user interaction required once the malicious content is stored. However, the vulnerability requires at least contributor-level authentication, limiting exploitation to users who already have some level of access to the WordPress site. No known public exploits are reported yet, and no patches have been published at the time of this analysis. The vulnerability is classified under CWE-79, which covers improper neutralization of input during web page generation, a common cause of XSS issues. Given the widespread use of WordPress and the popularity of social sharing plugins, this vulnerability poses a significant risk to websites using this plugin, especially those with multiple contributors or less stringent access controls.

For European organizations, this vulnerability can lead to unauthorized script execution within the context of their websites, potentially compromising user sessions, stealing sensitive information, or defacing web content. Organizations relying on WordPress for their public-facing websites or intranets that use the Html Social share buttons plugin are at risk. The impact is particularly critical for sectors handling sensitive user data, such as e-commerce, finance, healthcare, and government services, where trust and data integrity are paramount. Exploitation could damage brand reputation, lead to regulatory non-compliance under GDPR due to data leakage, and cause operational disruptions. Since the vulnerability requires contributor-level access, insider threats or compromised contributor accounts could be leveraged to exploit the flaw. Additionally, the stored nature of the XSS means that once injected, the malicious payload persists and affects all visitors to the compromised pages, amplifying the potential damage.

European organizations should immediately audit their WordPress installations to identify the presence of the Html Social share buttons plugin and verify the version in use. Until an official patch is released, organizations should consider disabling or removing the plugin to eliminate the attack vector. Implement strict access controls to limit contributor-level permissions only to trusted users and enforce strong authentication mechanisms, including multi-factor authentication, to reduce the risk of account compromise. Employ Web Application Firewalls (WAFs) with rules designed to detect and block XSS payloads targeting the plugin's shortcode parameters. Conduct regular security reviews and code audits for custom shortcodes or plugins that process user input. Additionally, educate contributors about secure content practices and monitor website content for unauthorized script injections. Once a patch becomes available, prioritize timely updates. For longer-term resilience, consider adopting Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on web pages.