CVE-2024-51754 is a vulnerability in Twig, a widely used PHP templating engine. The issue arises within Twig's sandbox security mechanism, which is designed to restrict the execution of certain methods to prevent unauthorized code execution or data exposure. Specifically, the vulnerability allows an attacker to invoke the __toString() magic method on an object even when the security policy explicitly disallows calling __toString(). This bypass occurs when the object is embedded within an array or passed as an argument to a function or filter within the Twig template. The consequence is an exposure of resources to an unintended scope, classified under CWE-668 (Exposure of Resource to Wrong Sphere). Although the vulnerability does not directly lead to code execution or privilege escalation, it can cause unintended information disclosure by allowing string conversion of objects that should be restricted. This flaw affects Twig versions prior to 3.11.2 and versions from 3.12.0 up to but not including 3.14.1. The issue has been patched in versions 3.11.2 and 3.14.1. There are no known workarounds, so upgrading is the only effective mitigation. The CVSS v3.1 base score is 2.2, indicating a low severity primarily due to the requirement of network access, high attack complexity, and the need for privileges (PR:H) without user interaction. The impact is limited to confidentiality with no integrity or availability impact. No known exploits are currently in the wild.

For European organizations, the impact of this vulnerability is relatively low but still noteworthy. Twig is commonly used in PHP-based web applications, including content management systems, e-commerce platforms, and custom web applications. An attacker who can inject or manipulate Twig templates in a sandboxed environment could exploit this vulnerability to gain unauthorized access to string representations of objects, potentially leaking sensitive information such as internal identifiers, configuration details, or other data encapsulated in objects. While this does not allow direct code execution or system compromise, information disclosure can aid attackers in reconnaissance or subsequent attacks. Organizations handling sensitive data or operating critical web services should be cautious, as even low-severity leaks can be leveraged in multi-stage attacks. The lack of known exploits reduces immediate risk, but the widespread use of Twig in Europe means that many organizations could be affected if attackers develop exploits.

The primary mitigation is to upgrade Twig to a patched version: 3.11.2 or later, or 3.14.1 or later if using versions between 3.12.0 and 3.14.1. Since no workarounds exist, organizations should prioritize updating their dependencies promptly. Additionally, organizations should audit their use of Twig sandboxing to ensure that untrusted user input cannot influence template rendering or object injection. Implement strict input validation and sanitization to prevent injection of malicious objects into templates. Monitoring and logging template rendering activities may help detect anomalous usage patterns. For environments where immediate upgrade is not feasible, consider isolating or restricting access to affected applications and applying web application firewall (WAF) rules to detect and block suspicious payloads targeting template injection. Finally, maintain an inventory of applications using Twig to ensure comprehensive patching.