CVE-2026-4766 identifies a stored Cross-Site Scripting (XSS) vulnerability in the Easy Image Gallery plugin for WordPress, affecting all versions up to and including 1.5.3. The root cause is insufficient sanitization and escaping of user-supplied input in the gallery shortcode post meta field. Authenticated attackers with Contributor-level privileges or higher can inject arbitrary JavaScript code into pages by manipulating the gallery shortcode values. When any user accesses the compromised page, the injected script executes in their browser context, potentially leading to session hijacking, defacement, or redirection to malicious sites. The vulnerability is exploitable remotely over the network without user interaction, with low attack complexity, and requires only limited privileges, which are commonly granted to contributors on WordPress sites. The vulnerability impacts confidentiality and integrity but not availability. No known public exploits have been reported yet, but the risk remains significant due to the widespread use of WordPress and the plugin. The vulnerability is tracked under CWE-79, highlighting improper neutralization of input during web page generation. The CVSS v3.1 base score is 6.4, reflecting medium severity with a scope change due to the impact on other users viewing the injected content. No official patches are currently linked, so mitigation may require manual intervention or plugin updates once available.

The primary impact of CVE-2026-4766 is the compromise of user confidentiality and integrity on websites using the Easy Image Gallery plugin. Attackers can execute arbitrary scripts in the context of the affected site, enabling theft of session cookies, credentials, or other sensitive information from users. This can lead to account takeover, unauthorized actions, or further exploitation of the site. The vulnerability affects all users who visit the injected pages, expanding the attack surface beyond the initial contributor attacker. While availability is not directly impacted, the reputational damage and potential data breaches can have severe consequences for organizations. Since Contributor-level access is relatively common on WordPress sites, the risk of exploitation is moderate to high, especially on sites with multiple content creators. The vulnerability could be leveraged in targeted attacks against organizations relying on this plugin for image gallery management, including media companies, bloggers, and e-commerce sites. The lack of known exploits in the wild suggests limited current exploitation but also indicates a window for proactive defense. Failure to address this vulnerability could result in data breaches, loss of user trust, and regulatory compliance issues related to data protection.

Organizations should immediately inventory their WordPress installations to identify the presence of the Easy Image Gallery plugin and verify the version in use. Until an official patch is released, administrators should restrict Contributor-level access to trusted users only, minimizing the risk of malicious shortcode injection. Implementing a Web Application Firewall (WAF) with rules to detect and block suspicious shortcode inputs can provide temporary protection. Site owners can also apply manual input validation and output encoding in the plugin code, specifically sanitizing gallery shortcode post meta fields to neutralize script tags and other malicious payloads. Monitoring site content for unexpected script injections and conducting regular security audits will help detect exploitation attempts. Once a vendor patch is available, prompt updating of the plugin is critical. Additionally, educating content contributors about safe input practices and limiting plugin usage to essential sites can reduce exposure. Backup procedures should be reviewed to ensure rapid recovery in case of compromise. Finally, consider deploying Content Security Policy (CSP) headers to restrict script execution sources, mitigating the impact of injected scripts.