CVE-2021-40925 in infaveo-helpdesk
Summary
by MITRE • 10/02/2021
Cross-site scripting (XSS) vulnerability in dompdf/dompdf/www/demo.php infaveo-helpdesk v1.11.0 and below allow remote attackers to inject arbitrary web script or HTML via the $_SERVER["PHP_SELF"] parameter.
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Analysis
by VulDB Data Team • 10/08/2021
The cross-site scripting vulnerability identified as CVE-2021-40925 affects the infaveo-helpdesk application version 1.11.0 and earlier, specifically within the dompdf/dompdf/www/demo.php component. This vulnerability stems from insufficient input validation and output encoding practices that fail to properly sanitize user-supplied data before incorporating it into web responses. The affected parameter $_SERVER["PHP_SELF"] represents the current script name as provided by the web server, making it susceptible to manipulation by remote attackers who can inject malicious scripts through this vector.
The technical flaw manifests when the application directly incorporates the $_SERVER["PHP_SELF"] value into HTML output without appropriate sanitization or encoding measures. This creates a classic reflected cross-site scripting condition where attacker-controlled input flows through the application's processing chain and gets executed in the victim's browser context. The vulnerability operates under CWE-79 which specifically addresses Cross-Site Scripting flaws, and aligns with ATT&CK technique T1203 for Exploitation for Client Execution. The flaw exists because the application does not implement proper output encoding or input validation mechanisms to prevent malicious payloads from being interpreted as executable code rather than plain text.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary scripts in the context of affected user sessions. An attacker could craft malicious URLs containing script payloads that, when visited by a victim, would execute in the victim's browser, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability affects all users of the affected helpdesk version, making it particularly dangerous in enterprise environments where multiple users interact with the system. Attackers could leverage this vulnerability to gain unauthorized access to sensitive information, modify user sessions, or perform actions on behalf of authenticated users.
Mitigation strategies for CVE-2021-40925 should prioritize immediate patching of the infaveo-helpdesk application to version 1.11.1 or later where the vulnerability has been addressed. Organizations should implement proper input validation and output encoding mechanisms throughout the application, specifically ensuring that all user-supplied data including server variables like $_SERVER["PHP_SELF"] are sanitized before being rendered in HTML contexts. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to limit script execution capabilities. Security teams should also conduct thorough code reviews to identify similar patterns in other application components and ensure that all server variables are properly escaped when used in HTML output contexts. Regular vulnerability scanning and penetration testing should be implemented to detect similar issues in other parts of the application infrastructure.