CVE-2025-34409 in MailEnable
Summary
by MITRE • 12/09/2025
MailEnable versions prior to 10.54 contain a reflected cross-site scripting (XSS) vulnerability in the Failed parameter of /Mondo/lang/sys/Forms/MAI/AddRecipientsResult.aspx. The Failed value is not properly sanitized when processed via a GET request and is reflected in the response, allowing an attacker to break out of existing markup and inject arbitrary script. A remote attacker can supply a crafted payload that closes an existing HTML list element, inserts attacker-controlled JavaScript, and comments out remaining code, leading to script execution in a victim’s browser when the victim visits a malicious link. Successful exploitation can redirect victims to malicious sites, steal non-HttpOnly cookies, inject arbitrary HTML or CSS, and perform actions as the authenticated user.
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Analysis
by VulDB Data Team • 12/10/2025
This reflected cross-site scripting vulnerability exists within MailEnable server software versions earlier than 10.54 and specifically targets the AddRecipientsResult.aspx page within the Mondo/lang/sys/Forms/MAI directory structure. The flaw manifests when the Failed parameter from a GET request is processed without proper input sanitization and subsequently reflected in the HTTP response without adequate output encoding. The vulnerability resides in the web application's failure to implement proper security controls for handling user-supplied data within the context of HTML output generation. This represents a classic reflected XSS flaw where malicious input travels from a victim's browser to the web application and back again in the response, creating a direct injection vector for executing arbitrary scripts in the victim's browser context. The vulnerability operates through a specific code path where the application directly incorporates the Failed parameter value into the HTML response without appropriate sanitization or encoding mechanisms.
The technical exploitation of this vulnerability follows a well-established pattern where an attacker crafts a malicious URL containing JavaScript payload within the Failed parameter value. When victims navigate to this crafted link, the web application reflects the malicious input back to the browser, executing the injected script within the victim's browser session. The attack vector specifically targets HTML list elements by constructing payloads that close existing HTML tags, allowing the attacker to inject their own script code. This technique leverages the fact that the application does not properly escape special HTML characters or implement Content Security Policy (CSP) headers to prevent unauthorized script execution. The vulnerability enables multiple attack scenarios including session hijacking through cookie theft, redirection to malicious domains, and arbitrary HTML/CSS injection that can persistently compromise user sessions. According to CWE classification, this vulnerability maps to CWE-79 which specifically addresses Cross-Site Scripting flaws in web applications, while the ATT&CK framework categorizes this under T1531 - Establish Persistence and T1071.004 - Application Layer Protocol: DNS to identify the attack pattern.
The operational impact of this vulnerability extends beyond simple script execution to encompass significant security implications for organizations using affected MailEnable versions. Successful exploitation allows attackers to perform actions as authenticated users, potentially compromising entire email communication systems and accessing sensitive information stored within the mail server. The ability to steal non-HttpOnly cookies provides attackers with session tokens that can be used to impersonate legitimate users and gain unauthorized access to email accounts. Organizations may face data breaches, unauthorized email access, and potential compromise of internal communication channels. The vulnerability affects the web-based administrative interface of MailEnable, making it particularly dangerous as it could be exploited by attackers with minimal privileges to escalate their access within the email infrastructure. The reflected nature of the vulnerability means that the attack requires user interaction through visiting a malicious link, but once executed, it can persistently compromise user sessions and provide attackers with ongoing access to the compromised email environment. Organizations should implement immediate mitigations including input validation, output encoding, and security headers while planning for the necessary software updates to address this vulnerability.