The vulnerability identified as CVE-2024-3340 affects the Colibri Page Builder plugin for WordPress, specifically versions up to and including 1.0.272. The issue is a stored cross-site scripting (XSS) flaw categorized under CWE-79, caused by improper neutralization of input during web page generation. The vulnerability exists in the 'colibri-gallery-slideshow' shortcode, where user-supplied attributes are not adequately sanitized or escaped before being rendered on pages. This allows an authenticated attacker with contributor-level or higher privileges to inject arbitrary JavaScript code into pages. When other users access these pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim. The attack vector requires no user interaction beyond viewing the compromised page, and the attacker does not need administrative privileges, only contributor-level access. The CVSS 3.1 base score is 5.4, reflecting network attack vector, low attack complexity, privileges required, no user interaction, and limited confidentiality and integrity impacts without availability impact. No known exploits have been reported in the wild yet, but the vulnerability poses a significant risk given the popularity of WordPress and the plugin. The lack of official patches at the time of publication necessitates immediate mitigation efforts by administrators.

The impact of CVE-2024-3340 is primarily on the confidentiality and integrity of affected WordPress sites using the Colibri Page Builder plugin. Successful exploitation allows attackers to execute arbitrary JavaScript in the context of the victim's browser, which can lead to theft of cookies, session tokens, or other sensitive information. It can also enable attackers to perform actions on behalf of users, potentially escalating privileges or defacing websites. Since the vulnerability requires contributor-level access, it can be exploited by malicious insiders or compromised contributor accounts. The widespread use of WordPress globally means many organizations, including businesses, media outlets, and government websites, could be affected. The vulnerability does not impact availability directly but can undermine user trust and lead to reputational damage. Without timely mitigation, attackers could leverage this flaw to conduct phishing, spread malware, or pivot to further attacks within the network.

1. Immediately restrict contributor-level access to trusted users only and audit existing contributor accounts for suspicious activity. 2. Until an official patch is released, disable or remove the 'colibri-gallery-slideshow' shortcode usage in pages to prevent exploitation. 3. Implement additional input validation and output escaping at the web application firewall (WAF) or reverse proxy level to detect and block malicious payloads targeting the shortcode parameters. 4. Monitor website logs and user activity for unusual behavior indicative of XSS exploitation attempts. 5. Educate content contributors about the risks of injecting untrusted content and enforce strict content submission policies. 6. Regularly update the Colibri Page Builder plugin once a security patch is available from the vendor. 7. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on the website. 8. Conduct security assessments and penetration testing focused on XSS vulnerabilities in custom shortcodes and plugins.