CVE-2025-32014 in estree-util-value-to-estree
Summary
by MITRE • 04/07/2025
estree-util-value-to-estree converts a JavaScript value to an ESTree expression. When generating an ESTree from a value with a property named __proto__, valueToEstree would generate an object that specifies a prototype instead. This vulnerability is fixed in 3.3.3.
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Analysis
by VulDB Data Team • 04/08/2025
The vulnerability identified as CVE-2025-32014 affects the estree-util-value-to-estree library, which serves as a utility for converting JavaScript values into ESTree expression format. This library operates within the broader ecosystem of JavaScript parsing and AST manipulation tools that are essential for code analysis, transformation, and security scanning applications. The flaw manifests when processing JavaScript objects containing a property explicitly named _proto_, which represents a special property in JavaScript that controls the prototype chain of objects. This particular vulnerability demonstrates a critical misunderstanding in how prototype properties are handled during the conversion process, creating potential security implications for applications that rely on this library for safe code processing.
The technical implementation flaw occurs within the valueToEstree function where the library fails to properly distinguish between regular object properties and the special _proto_ property. When encountering an object with a _proto_ property, the function incorrectly interprets this as a prototype specification rather than a regular property assignment. This misinterpretation leads to the generation of ESTree nodes that contain prototype chain manipulation instructions instead of standard property assignments. The vulnerability essentially allows an attacker to inject prototype pollution behavior through what appears to be normal JavaScript value conversion operations, creating a potential vector for prototype pollution attacks that can affect applications relying on this library for parsing or analysis.
The operational impact of this vulnerability extends beyond simple parsing errors as it introduces a prototype pollution risk that can affect applications using the estree-util-value-to-estree library. Prototype pollution vulnerabilities are particularly dangerous because they can lead to various security issues including remote code execution, denial of service, and privilege escalation depending on how the parsed code is subsequently used. The vulnerability maps to CWE-471, which specifically addresses the issue of "Incorrectly Handling of Special Values" in the context of prototype handling. Applications that use this library for processing untrusted input, such as code analysis tools, linters, or security scanners, could be exposed to prototype pollution attacks that might compromise the integrity of the processing environment.
Security practitioners should consider this vulnerability in the context of the ATT&CK framework, particularly under the techniques related to "Prototype Pollution" and "Code Injection" where this flaw could enable attackers to manipulate object prototypes in unexpected ways. The fix implemented in version 3.3.3 addresses this by properly distinguishing between prototype specification and property assignment during the ESTree generation process. Organizations using this library should immediately upgrade to version 3.3.3 or later to mitigate the risk, as the vulnerability does not require any special privileges or complex attack vectors to exploit. The remediation process involves updating the library dependency and ensuring that all applications relying on this functionality are properly tested to confirm that the prototype pollution behavior has been eliminated. This vulnerability serves as a reminder of the importance of proper handling of special JavaScript properties and the potential security implications when these properties are not correctly interpreted during AST generation processes.