CVE-2026-23615 is a stored cross-site scripting (XSS) vulnerability identified in GFI Software's MailEssentials AI product, specifically affecting versions prior to 22.4. The vulnerability resides in the Sender Policy Framework (SPF) Email Exceptions interface, where the parameter ctl00$ContentPlaceHolder1$pv4$txtEmailDescription accepts user-supplied input. An authenticated user can inject malicious HTML or JavaScript code into this parameter, which is then stored persistently and rendered later in the web-based management interface without adequate sanitization or encoding. This improper neutralization of input during web page generation corresponds to CWE-79. When a legitimate administrator or user accesses the affected interface, the malicious script executes in their browser context, potentially allowing the attacker to hijack sessions, steal credentials, perform unauthorized actions, or pivot further into the system. The vulnerability requires authentication but no elevated privileges beyond that, and no additional user interaction is necessary beyond viewing the affected page. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, partial user interaction, and limited confidentiality and integrity impact. No public exploits or patches are currently available, but the vulnerability poses a moderate risk given the administrative context of the affected interface. Organizations relying on MailEssentials AI should monitor for updates and consider interim mitigations such as restricting access to the management interface, implementing web application firewalls with XSS protections, and auditing user inputs.

The primary impact of this vulnerability is the potential compromise of the MailEssentials AI management interface, which is typically used by administrators to configure email security policies. Successful exploitation could allow an attacker to execute arbitrary scripts in the context of an authenticated user, leading to session hijacking, credential theft, or unauthorized configuration changes. This could degrade the integrity and confidentiality of the email security environment, potentially allowing malicious emails to bypass filters or enabling further lateral movement within the organization. While availability impact is limited, the breach of administrative controls can have cascading effects on overall organizational security posture. Given that the vulnerability requires authentication, the risk is somewhat mitigated but remains significant in environments with multiple users or weak access controls. Organizations worldwide using GFI MailEssentials AI, especially those with large or distributed administrative teams, could face targeted attacks exploiting this flaw to undermine their email security defenses.

1. Upgrade to GFI MailEssentials AI version 22.4 or later once a patch is released to address this vulnerability. 2. Until a patch is available, restrict access to the Sender Policy Framework Email Exceptions interface to trusted administrators only, using network segmentation, VPNs, or IP whitelisting. 3. Implement strict input validation and output encoding on the txtEmailDescription parameter to prevent injection of malicious scripts. 4. Deploy a web application firewall (WAF) with rules specifically targeting stored XSS attacks to detect and block malicious payloads. 5. Conduct regular audits of user inputs and stored data in the management interface to identify and remove any injected scripts. 6. Enforce strong authentication mechanisms and monitor administrative user activity for suspicious behavior. 7. Educate administrators about the risks of XSS and encourage cautious handling of input fields. 8. Consider implementing Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within the management interface.