CVE-2024-35226 is a code injection vulnerability classified under CWE-94 affecting the Smarty PHP template engine, a widely used tool that separates presentation logic from application logic. The vulnerability arises from improper control over the generation of code via the extends-tag in templates. Specifically, a malicious template author can craft a filename for the extends-tag that includes PHP code, which Smarty then executes, leading to arbitrary code execution within the context of the web server. This flaw affects Smarty versions from 3.0.0 up to but not including 4.5.3, and versions from 5.0.0 up to but not including 5.1.1. Notably, there is no patch available for users on the v3 branch, and no known workarounds exist, making upgrading or restricting template author capabilities critical. The vulnerability requires at least limited privileges (template author role) and user interaction to exploit, but once exploited, it can compromise confidentiality and integrity of the application and underlying system. The CVSS v3.1 score is 7.3, reflecting high severity due to network attack vector, low attack complexity, required privileges, and user interaction. No known exploits are currently observed in the wild, but the risk remains significant given the potential impact and lack of mitigations for older branches.

For European organizations, the impact of CVE-2024-35226 can be severe, particularly for those relying on Smarty in web applications that allow multiple template authors or third-party template contributions. Successful exploitation can lead to arbitrary PHP code execution, enabling attackers to access sensitive data, modify application behavior, or pivot to further internal network compromise. Confidentiality is at high risk as attackers can read sensitive configuration files or databases. Integrity is also highly impacted since attackers can alter application logic or data. Although availability impact is not directly indicated, secondary effects such as data corruption or service disruption could occur. Organizations in sectors with high web presence such as finance, e-commerce, government, and media are especially vulnerable. The lack of patches for older versions means legacy systems remain exposed, increasing the attack surface. Given the widespread use of PHP and Smarty in Europe, the threat could affect a broad range of enterprises and public sector entities.

1. Upgrade Smarty to the latest patched versions: For v4 and v5 branches, update to versions >=4.5.3 and >=5.1.1 respectively as soon as they become available. 2. For users on the unsupported v3 branch, consider migrating to a supported version promptly since no patches exist. 3. Restrict template author privileges strictly to trusted personnel only; avoid allowing untrusted or external contributors to upload or modify templates. 4. Implement rigorous input validation and sanitization on template filenames and any user-supplied data used in templates to prevent injection of malicious code. 5. Employ runtime application self-protection (RASP) or web application firewalls (WAFs) with custom rules to detect and block suspicious template-related requests. 6. Conduct code reviews and security audits of templates before deployment to identify potential injection vectors. 7. Monitor logs for unusual template loading or execution patterns that could indicate exploitation attempts. 8. Isolate web application environments to limit the impact of potential code execution. 9. Educate developers and template authors about secure template practices and the risks of code injection.