CVE-2020-36604 in hoek
Summary
by MITRE • 09/23/2022
hoek before 8.5.1 and 9.x before 9.0.3 allows prototype poisoning in the clone function.
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Analysis
by VulDB Data Team • 05/28/2025
The vulnerability identified as CVE-2020-36604 affects the hoek library, a core dependency used extensively in node.js applications for object manipulation and utility functions. This issue represents a prototype poisoning vulnerability that exists in versions prior to 8.5.1 and 9.x before 9.0.3, making it a critical concern for developers who rely on this library for object cloning operations. The flaw specifically manifests within the clone function of the hoek library, which is designed to create deep copies of objects but inadvertently allows malicious actors to manipulate the prototype chain of objects being cloned.
The technical root cause of this vulnerability stems from improper handling of object properties during the cloning process. When the clone function processes objects that contain properties with special names such as constructor or _proto_, it fails to properly sanitize these values, allowing attackers to inject malicious code into the prototype chain. This behavior aligns with CWE-1321, which categorizes prototype pollution vulnerabilities, and represents a classic example of insecure object manipulation where developer assumptions about object property handling are exploited. The vulnerability enables attackers to modify the behavior of built-in JavaScript objects by manipulating their prototypes, potentially leading to arbitrary code execution or other security breaches.
The operational impact of CVE-2020-36604 extends beyond simple object manipulation issues, as it can enable attackers to gain unauthorized access to sensitive data or manipulate application behavior in ways that compromise system integrity. Applications using vulnerable versions of hoek may be susceptible to remote code execution if the cloned objects are later used in contexts that evaluate or execute code based on their properties. This vulnerability particularly affects server-side applications where user input is processed through hoek's clone function, as attackers can craft malicious payloads that exploit the prototype poisoning to alter object behavior. The attack vector typically involves providing specially crafted input that contains properties designed to poison the prototype chain during the cloning operation, which can then be leveraged in subsequent operations to achieve the attacker's objectives.
Mitigation strategies for this vulnerability require immediate updates to the hoek library to versions 8.5.1 or 9.0.3 and later, which contain the necessary patches to prevent prototype poisoning during cloning operations. Security teams should conduct comprehensive audits of their dependency trees to identify all applications and services that utilize vulnerable versions of hoek, as this library is often used transitively through other packages. The remediation process should include not only updating the hoek library but also implementing proper input validation and sanitization practices to prevent similar issues in other parts of the application stack. Organizations should consider implementing dependency monitoring tools and security scanning processes to detect vulnerable components proactively, as this vulnerability demonstrates how seemingly innocuous utility functions can become attack vectors in complex software ecosystems. This case study exemplifies the importance of proper object handling in JavaScript applications and aligns with ATT&CK technique T1059.006 for execution through JavaScript, highlighting how prototype pollution can enable arbitrary code execution in vulnerable environments.