CVE-2021-40923 in bugs
Summary
by MITRE • 10/02/2021
Cross-site scripting (XSS) vulnerability in install/index.php in bugs 1.8 and below version allows remote attackers to inject arbitrary web script or HTML via the email parameter.
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Analysis
by VulDB Data Team • 10/08/2021
The CVE-2021-40923 vulnerability represents a critical cross-site scripting flaw within the bugs application version 1.8 and earlier, specifically affecting the install/index.php file. This vulnerability resides in the application's input validation mechanisms, where user-supplied data from the email parameter is not properly sanitized before being processed or displayed within the web interface. The flaw allows remote attackers to execute malicious scripts in the context of other users' browsers, potentially leading to session hijacking, credential theft, or unauthorized actions within the application environment.
This vulnerability maps directly to CWE-79, which defines Cross-Site Scripting as a weakness where an application fails to properly validate or escape user input before incorporating it into dynamically generated web pages. The specific exploitation vector involves the email parameter in the installation script, suggesting that the vulnerability exists in the application's initial setup phase where user input is accepted without adequate sanitization. The attack occurs when an attacker crafts a malicious email address containing embedded script tags that execute upon page rendering, leveraging the application's failure to implement proper output encoding or input validation.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged to compromise user sessions and potentially escalate privileges within the application. An attacker could craft a malicious email parameter that, when processed by the vulnerable installation script, would execute malicious JavaScript code in the victim's browser. This could result in the theft of session cookies, redirection to malicious sites, or modification of application data. The vulnerability is particularly dangerous in the installation phase as it may affect administrators who are setting up the application, potentially allowing attackers to gain unauthorized access to the installation process or compromise the entire system during its initial configuration.
Mitigation strategies for CVE-2021-40923 should focus on implementing robust input validation and output encoding mechanisms throughout the application. Organizations should immediately upgrade to a patched version of the bugs application, as version 1.9 and later should contain the necessary security fixes. In the interim, administrators should implement proper input sanitization by escaping special characters in user-supplied email addresses, implementing Content Security Policy headers to limit script execution, and conducting thorough input validation to reject malformed email addresses. The ATT&CK framework categorizes this vulnerability under T1566, specifically targeting the initial access phase through credential access and privilege escalation techniques. Additionally, implementing proper web application firewall rules to detect and block malicious payloads in email parameters can provide an additional layer of defense against exploitation attempts.