CVE-2021-3983 in kimai2
Summary
by MITRE • 12/01/2021
kimai2 is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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Analysis
by VulDB Data Team • 12/08/2021
Kimai2 represents a time tracking application that has been identified with a critical cross-site scripting vulnerability categorized as CVE-2021-3983. This vulnerability stems from improper input validation during web page generation processes, creating an avenue for malicious actors to inject arbitrary javascript code into the application's user interface. The flaw specifically manifests when user-supplied data is not adequately sanitized before being rendered in web pages, allowing attackers to execute malicious scripts in the context of other users' browsers.
The technical implementation of this vulnerability aligns with CWE-79 which defines cross-site scripting as a code injection attack where malicious scripts are executed in the victim's browser. The vulnerability occurs within kimai2's web rendering pipeline where input parameters are directly incorporated into HTML output without proper encoding or sanitization measures. Attackers can exploit this weakness by crafting malicious input strings that contain javascript payloads, which then get executed when other users view the affected pages or interact with the application's interface.
Operational impact of this vulnerability extends beyond simple data theft or session hijacking. The compromised system allows attackers to perform actions on behalf of legitimate users, potentially leading to unauthorized access to time tracking data, modification of project records, or even complete account takeover. The vulnerability affects all users of kimai2 who have access to input fields or areas where user-generated content is displayed, making it particularly dangerous in collaborative environments where multiple users interact with shared time tracking records. Additionally, the attack can be delivered through various vectors including web forms, URL parameters, or even through stored data in the application's database.
Security mitigations for CVE-2021-3983 should focus on implementing comprehensive input sanitization and output encoding mechanisms throughout the application's codebase. The recommended approach includes applying proper html encoding to all user-supplied content before rendering in web pages, implementing content security policies to restrict script execution, and utilizing parameterized queries to prevent injection attacks. Organizations should also consider implementing web application firewalls to detect and block malicious payloads, while ensuring regular security updates and patches are applied to the kimai2 application. The vulnerability demonstrates the importance of following secure coding practices and adhering to OWASP Top Ten security guidelines for preventing cross-site scripting attacks. Mitigation strategies should also include user education on recognizing potentially malicious input and implementing strict access controls to limit the impact of any successful exploitation attempts.