CVE-2024-28191 in Contao
Summary
by MITRE • 04/09/2024
Contao is an open source content management system. Starting in version 4.0.0 and prior to version 4.13.40 and 5.3.4, it is possible to inject insert tags in frontend forms if the output is structured in a very specific way. Contao versions 4.13.40 and 5.3.4 have a patch for this issue. As a workaround, do not output user data from frontend forms next to each other, always separate them by at least one character.
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Analysis
by VulDB Data Team • 04/07/2025
The vulnerability identified as CVE-2024-28191 affects Contao content management systems across multiple versions, representing a significant security flaw that could enable arbitrary code execution through carefully crafted input. This issue stems from improper handling of insert tags within frontend forms, specifically when user-provided data is processed and rendered in a particular structural arrangement. The vulnerability exists in versions 4.0.0 through 4.13.39 and 5.0.0 through 5.3.3, making it a widespread concern for organizations relying on these CMS versions. The flaw manifests when insert tags are processed in a specific pattern that allows attackers to manipulate the rendering pipeline, potentially leading to privilege escalation and unauthorized access to system resources.
The technical exploitation of this vulnerability involves manipulating frontend form submissions to inject malicious insert tags that can be executed during template rendering. This type of vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and falls under the broader category of injection flaws. The attack vector requires that user data from frontend forms be output in a specific arrangement where insert tags can be interpreted and executed by the CMS engine. The vulnerability's impact is particularly concerning as it can be leveraged to execute arbitrary commands on the server, potentially leading to complete system compromise. Attackers can exploit this by crafting form submissions that contain specially formatted insert tags, which when rendered in the affected versions can trigger unintended code execution.
The operational impact of this vulnerability extends beyond simple data manipulation, as it can enable attackers to gain unauthorized access to sensitive system information and potentially escalate privileges within the CMS environment. Organizations using affected Contao versions face risks of data breaches, system compromise, and potential regulatory violations due to the exposure of sensitive user information. The vulnerability's exploitation requires minimal privileges and can be executed through standard web browser interactions, making it particularly dangerous for public-facing applications. This flaw creates a persistent security risk that can be exploited by both authenticated and unauthenticated attackers, depending on the specific implementation and configuration of the affected systems.
Mitigation strategies for this vulnerability include immediate patching to versions 4.13.40 and 5.3.4, which contain the necessary security fixes. Organizations should also implement the recommended workaround of separating user data output by at least one character to prevent the specific rendering pattern that enables the exploit. Security teams should conduct comprehensive vulnerability assessments to identify all instances of affected Contao installations within their infrastructure and ensure proper access controls are implemented. The remediation process should include monitoring for potential exploitation attempts and reviewing system logs for suspicious activities. Additionally, organizations should consider implementing web application firewalls and input validation mechanisms to provide additional layers of protection against similar injection attacks. This vulnerability demonstrates the importance of proper input sanitization and output encoding in web applications, particularly in CMS platforms where user-generated content is frequently processed and rendered.