CVE-2022-26114 in FortiMail
Summary
by MITRE • 09/06/2022
An improper neutralization of input during web page generation vulnerability [CWE-79] in the Webmail of FortiMail before 7.2.0 may allow an unauthenticated attacker to trigger a cross-site scripting (XSS) attack via sending specially crafted mail messages.
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Analysis
by VulDB Data Team • 10/14/2022
The vulnerability identified as CVE-2022-26114 represents a critical cross-site scripting flaw in FortiMail's webmail interface that affects versions prior to 7.2.0. This weakness stems from inadequate input validation and sanitization during web page generation processes, creating a pathway for malicious actors to execute arbitrary JavaScript code within the context of a victim's browser session. The vulnerability specifically manifests when the webmail system processes incoming email messages that contain maliciously crafted content, particularly in headers or body fields that are subsequently rendered in web interfaces without proper neutralization. The issue falls under CWE-79, which categorizes cross-site scripting vulnerabilities as a result of insufficient sanitization of user-supplied data, making it a well-documented and severe class of web application security flaws that can lead to session hijacking, data theft, and privilege escalation.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to manipulate the webmail interface in ways that can compromise user sessions and access sensitive email communications. An unauthenticated attacker can exploit this flaw by simply sending a specially crafted email message that contains malicious JavaScript payloads, which then gets rendered when users view the message within the vulnerable FortiMail webmail environment. This attack vector is particularly dangerous because it requires no authentication from the attacker's perspective, and the malicious code executes in the context of the victim's logged-in session, potentially allowing for complete account compromise and unauthorized access to all email communications. The vulnerability demonstrates a fundamental breakdown in the application's security architecture where user-provided content is not adequately sanitized before being displayed in web contexts, creating an environment where persistent XSS attacks can occur.
Security professionals should recognize this vulnerability as a prime example of how input validation failures can create persistent security risks in web applications, particularly in email systems where users expect to process untrusted content. The flaw represents a classic case of insufficient output escaping or encoding during web page generation, where data from external sources flows directly into HTML output without proper context-aware sanitization. Organizations using FortiMail versions prior to 7.2.0 should immediately implement mitigations including applying the vendor's security patches, implementing web application firewalls, and considering additional input filtering measures. The vulnerability aligns with ATT&CK technique T1566.001 which covers spearphishing attachments, as attackers can leverage this flaw to deliver malicious payloads through email content. Additionally, the issue demonstrates how webmail systems require robust security controls to prevent user-supplied data from being interpreted as executable code, particularly in environments where users may encounter untrusted email content from external sources.
The remediation approach should involve immediate patch management to upgrade to FortiMail version 7.2.0 or later, which contains the necessary fixes for this vulnerability. Organizations should also implement comprehensive input validation policies that enforce strict sanitization of all user-supplied data before rendering in web contexts. Network segmentation and access controls can provide additional defense-in-depth measures, while security monitoring should be enhanced to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and implementing robust input validation mechanisms in web applications, particularly in email systems where the volume and variety of user-supplied content creates numerous potential attack surfaces. Organizations should also consider implementing Content Security Policy headers and other browser-based protections to limit the impact of potential XSS exploitation attempts, even when application-level fixes are not immediately available.