CVE-2020-5259 in dojox
Summary
by MITRE
In affected versions of dojox (NPM package), the jqMix method is vulnerable to Prototype Pollution. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. This has been patched in versions 1.11.10, 1.12.8, 1.13.7, 1.14.6, 1.15.3 and 1.16.2
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-5259 affects the dojox JavaScript library, specifically within the jqMix method that handles object merging operations. This issue represents a classic prototype pollution vulnerability that exploits the fundamental nature of JavaScript object prototypes, where attackers can manipulate the prototype chain to inject malicious properties into core JavaScript objects. The vulnerability stems from inadequate input validation during object property assignment operations, allowing attackers to inject arbitrary properties into the Object.prototype, which then propagates to all objects inheriting from it. The affected versions of the dojox library demonstrate a critical flaw in how they handle object merging, particularly when processing user-supplied data through the jqMix function.
The technical exploitation of this vulnerability occurs when the jqMix method processes objects containing malicious property names that are designed to pollute the prototype chain. When an attacker supplies crafted input containing properties like "_proto_" or "constructor", these values can be directly assigned to the prototype, allowing the attacker to modify the behavior of all objects that inherit from Object.prototype. This type of vulnerability falls under CWE-471, which specifically addresses the weakness of "Modification of Assumed-Immutable Data", and represents a significant security risk as it can lead to various downstream attacks including remote code execution, denial of service, or data manipulation. The vulnerability is particularly dangerous because it operates at the foundational level of JavaScript's object model, making it difficult to detect and mitigate.
The operational impact of this prototype pollution vulnerability extends beyond simple data corruption, as it can enable sophisticated attack vectors that leverage the prototype chain to execute malicious code. When applications using vulnerable versions of dojox process user input through the jqMix method, attackers can manipulate the prototype to inject properties that alter the behavior of core JavaScript functions or objects. This can result in various attack scenarios including but not limited to bypassing security controls, manipulating object properties in unexpected ways, or even achieving remote code execution in certain contexts. The vulnerability affects applications that rely on the dojox library for object manipulation, particularly those that process untrusted input through the affected methods. According to ATT&CK framework, this vulnerability maps to T1059.007 for JavaScript and T1566 for malicious input, as it enables attackers to inject malicious code through prototype pollution.
Mitigation strategies for CVE-2020-5259 primarily involve upgrading to patched versions of the dojox library, specifically versions 1.11.10, 1.12.8, 1.13.7, 1.14.6, 1.15.3, and 1.16.2 where the prototype pollution vulnerability has been addressed. Organizations should conduct thorough dependency audits to identify all applications using vulnerable versions of the library and implement immediate upgrades. Additional defensive measures include implementing input validation and sanitization at multiple layers, particularly when processing user-supplied data that may be passed to object merging functions. Security teams should also consider implementing prototype pollution detection mechanisms and monitoring for unusual property assignments to object prototypes. The vulnerability highlights the importance of proper input validation and the need for developers to be aware of prototype pollution attack vectors, as it demonstrates how seemingly benign object manipulation functions can become security risks when not properly secured against malicious input.