CVE-2023-46245 in Kimai
Summary
by MITRE • 10/31/2023
Kimai is a web-based multi-user time-tracking application. Versions 2.1.0 and prior are vulnerable to a Server-Side Template Injection (SSTI) which can be escalated to Remote Code Execution (RCE). The vulnerability arises when a malicious user uploads a specially crafted Twig file, exploiting the software's PDF and HTML rendering functionalities. As of time of publication, no patches or known workarounds are available.
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Analysis
by VulDB Data Team • 11/24/2023
The vulnerability identified as CVE-2023-46245 represents a critical Server-Side Template Injection flaw in Kimai version 2.1.0 and earlier, presenting a severe risk to organizations utilizing this web-based time-tracking application. This vulnerability exists within the application's PDF and HTML rendering functionalities, creating an attack vector that allows malicious actors to upload specially crafted Twig template files. The flaw stems from insufficient input validation and sanitization mechanisms within the template processing pipeline, enabling unauthorized users to inject malicious template code that executes on the server. Given that Kimai is designed for multi-user environments, this vulnerability can be exploited by any authenticated user with upload privileges, making it particularly dangerous in shared or enterprise deployments where multiple users have varying levels of access.
The technical exploitation of this SSTI vulnerability escalates to Remote Code Execution capabilities, allowing attackers to execute arbitrary commands on the affected server. The attack leverages the Twig templating engine's functionality where user-supplied content is processed without proper sanitization, enabling the injection of malicious template syntax that translates into executable server-side code. This represents a direct violation of the principle of least privilege and input validation, as the application fails to properly isolate user-generated content from the execution environment. The vulnerability's impact is amplified by the fact that it requires minimal privileges to exploit, as users only need the ability to upload files through the application's legitimate interfaces. The lack of available patches or workarounds at the time of publication leaves affected organizations with limited immediate remediation options, forcing them to implement compensating controls or temporary network-level restrictions.
Organizations deploying Kimai versions prior to 2.1.1 face significant operational risks due to this vulnerability, as it can lead to complete system compromise and data breaches. The attack surface extends beyond simple code execution to include potential privilege escalation, lateral movement within networks, and persistence mechanisms that attackers can establish. This vulnerability aligns with CWE-94, which describes the weakness of allowing code to be executed in the context of the application, and represents a clear violation of the OWASP Top Ten's A03:2021 - Injection flaws, specifically targeting template injection vectors. The ATT&CK framework categorizes this vulnerability under T1059.001 for command and script injection, with potential progression to T1078 for valid accounts and T1566 for spearphishing with a malicious attachment, as attackers may leverage the RCE capability to establish persistent access and exfiltrate sensitive time-tracking data.
The exploitation of this vulnerability requires careful consideration of the application's architecture and user privilege model, as it demonstrates how legitimate application features can become attack vectors when proper security controls are absent. Organizations should implement immediate network segmentation to limit access to Kimai applications, restrict upload capabilities to minimal required users, and monitor for suspicious file uploads or unusual system behavior. The vulnerability also highlights the importance of secure template processing and input validation in web applications, particularly those handling user-generated content. Security teams must conduct comprehensive assessments of their Kimai deployments, identify all instances of vulnerable versions, and implement either network-level firewalls, web application firewalls, or application-level restrictions to prevent template injection attacks. Additionally, organizations should consider implementing automated monitoring for file upload activities and establish incident response procedures specifically addressing template injection vulnerabilities to minimize potential damage from exploitation attempts.