CVE-2023-25344 in swig-templates
Summary
by MITRE • 03/15/2023
An issue was discovered in swig-templates thru 2.0.4 and swig thru 1.4.2, allows attackers to execute arbitrary code via crafted Object.prototype anonymous function.
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Analysis
by VulDB Data Team • 10/30/2025
This vulnerability exists in the swig-templates and swig template engines versions 2.0.4 and earlier, as well as swig versions 1.4.2 and earlier. The flaw resides in how these template engines handle object prototypes during template compilation and rendering processes. Attackers can exploit this vulnerability by crafting malicious input that manipulates the Object.prototype anonymous function, which allows them to inject and execute arbitrary code within the context of the application using these template engines. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly handle prototype pollution attacks, where malicious data can be injected into the prototype chain of objects used by the template engine.
The technical exploitation of this vulnerability occurs when an attacker provides specially crafted input that modifies the Object.prototype properties during template processing. This manipulation enables the execution of arbitrary JavaScript code because the template engine does not properly sanitize or validate the prototype chain of objects. The vulnerability is particularly dangerous because it allows attackers to execute code in the context of the application server, potentially leading to complete system compromise. The attack vector typically involves passing malicious data through template variables or parameters that get processed through the vulnerable template engine. This type of vulnerability falls under the CWE-471 category of "Modification of Assumed-Immutable Data" and represents a prototype pollution attack pattern that has been documented in various security frameworks including the OWASP Top 10.
The operational impact of this vulnerability is severe as it can lead to full system compromise when exploited. An attacker who successfully exploits this vulnerability can execute arbitrary code on the target system, potentially gaining access to sensitive data, performing unauthorized operations, or even establishing persistent backdoors. The vulnerability affects web applications that use swig or swig-templates for rendering dynamic content, making it particularly dangerous in environments where user input is processed through templates. Applications running on Node.js environments are especially at risk since these template engines are commonly used in server-side rendering contexts. The attack can result in data breaches, service disruption, and unauthorized access to system resources, with potential implications for business continuity and regulatory compliance.
Mitigation strategies for this vulnerability include immediate upgrading to patched versions of swig and swig-templates where available, as the maintainers have released updates addressing the prototype pollution issue. Organizations should implement strict input validation and sanitization measures to prevent malicious data from reaching the template engine processing layers. Additionally, implementing proper content security policies, using secure coding practices that avoid direct prototype manipulation, and conducting regular security assessments of template engine usage can help reduce the risk of exploitation. The vulnerability demonstrates the importance of following secure coding guidelines and maintaining up-to-date dependencies, as outlined in the MITRE ATT&CK framework's techniques for prototype pollution and code injection attacks. Organizations should also consider implementing runtime protections and monitoring mechanisms to detect potential exploitation attempts and ensure comprehensive defense-in-depth strategies are in place.