CVE-2024-38454 in ExpressionEngine
Summary
by MITRE • 06/16/2024
ExpressionEngine before 7.4.11 allows XSS.
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Analysis
by VulDB Data Team • 06/07/2026
ExpressionEngine versions prior to 7.4.11 contain a cross-site scripting vulnerability that arises from insufficient input validation and output encoding within the application's content management framework. This vulnerability exists in the way the system processes user-supplied data when rendering content, particularly in areas where HTML content is accepted and displayed without proper sanitization. The flaw allows attackers to inject malicious scripts into web pages viewed by other users, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of victims. The vulnerability stems from inadequate protection against malicious input in form fields, content editors, and other user-facing components that handle HTML content. Attackers can exploit this weakness by crafting specially formatted input that includes script tags or other malicious code sequences, which then get executed in the browsers of unsuspecting users who view the affected content. This issue represents a classic case of insufficient output escaping as defined by CWE-79, where the application fails to properly encode data before rendering it in the browser context. The vulnerability aligns with ATT&CK technique T1531 which focuses on use of remote services for data exfiltration and command execution through web application flaws. The impact of this vulnerability extends beyond simple script execution as it can enable more sophisticated attacks including phishing campaigns, cookie theft, and potential privilege escalation within the application environment. Organizations running affected versions of ExpressionEngine face significant risk of unauthorized access and data compromise, particularly in environments where the application handles sensitive user information or administrative content. The vulnerability is particularly concerning because it affects core content management functionality and can be exploited through multiple vectors including user comments, content fields, and administrative interfaces. The flaw demonstrates a failure in the application's defense-in-depth strategy, where input validation should occur at multiple layers to prevent malicious data from being processed or displayed. Security researchers have identified that the vulnerability can be exploited through various attack vectors including direct input manipulation, file upload processes, and API endpoints that handle user-generated content. The exploitation requires minimal technical skill and can be automated, making it particularly dangerous in environments with multiple users or public-facing content management systems. Organizations should prioritize updating to ExpressionEngine 7.4.11 or later versions to remediate this vulnerability and ensure proper input sanitization and output encoding mechanisms are in place. The fix implemented in the patched version addresses the root cause by introducing more robust validation and encoding procedures for user-supplied content, particularly in HTML rendering contexts. Additionally, implementing proper content security policies and regular security assessments can help prevent similar vulnerabilities from emerging in the application's codebase. The vulnerability serves as a reminder of the critical importance of input validation and output encoding in web applications, particularly in content management systems where user-generated content is a core feature. Organizations should also consider implementing web application firewalls and monitoring systems to detect and prevent exploitation attempts targeting known vulnerabilities in their web applications. The security implications of this flaw extend to potential compliance violations in environments governed by regulations such as gdpr, hipaa, or pci dss, where inadequate protection of user data can result in significant penalties and legal consequences.