CVE-2025-64718
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-11-13

Last updated on: 2025-12-02

Assigner: GitHub, Inc.

Description
js-yaml is a JavaScript YAML parser and dumper. In js-yaml 4.1.0 and below, it's possible for an attacker to modify the prototype of the result of a parsed yaml document via prototype pollution (`__proto__`). All users who parse untrusted yaml documents may be impacted. The problem is patched in js-yaml 4.1.1. Users can protect against this kind of attack on the server by using `node --disable-proto=delete` or `deno` (in Deno, pollution protection is on by default).
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Meta Information
Published
2025-11-13
Last Modified
2025-12-02
Generated
2026-06-16
AI Q&A
2025-11-13
EPSS Evaluated
2026-06-15
NVD
CVE-2025-64718
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
nodeca js-yaml to 4.1.1 (exc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-1321 The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
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Executive Summary

This vulnerability in js-yaml versions 4.1.0 and below allows an attacker to modify the prototype of the object resulting from parsing a YAML document through prototype pollution using the __proto__ property. This means that if an attacker provides a malicious YAML document, they can manipulate the internal structure of the parsed object, potentially leading to unexpected behavior or security issues.

Impact Analysis

If you parse untrusted YAML documents using vulnerable versions of js-yaml, an attacker could exploit this vulnerability to perform prototype pollution, which may lead to altered application behavior or security risks. This could affect the integrity of your application and potentially allow further attacks depending on how the parsed data is used.

Mitigation Strategies

To mitigate this vulnerability, update js-yaml to version 4.1.1 or later. Additionally, on the server side, you can protect against prototype pollution by running Node.js with the flag `--disable-proto=delete`. Using Deno is also a mitigation option since it has pollution protection enabled by default.

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