CVE-2025-64718
MEDIUMCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Lifecycle Timeline
3Description
js-yaml is a JavaScript YAML parser and dumper. In js-yaml before 4.1.1 and 3.14.2, 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 and 3.14.2. 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).
Analysis
js-yaml is a JavaScript YAML parser and dumper. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) vulnerability could allow attackers to modify object prototypes to inject properties affecting application logic.
Technical Context
This vulnerability is classified as Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (CWE-1321), which allows attackers to modify object prototypes to inject properties affecting application logic. js-yaml is a JavaScript YAML parser and dumper. In js-yaml before 4.1.1 and 3.14.2, 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 and 3.14.2. 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). Affected products include: Nodeca Js-Yaml. Version information: before 4.1.1.
Affected Products
Nodeca Js-Yaml.
Remediation
A vendor patch is available. Apply the latest security update as soon as possible. Freeze prototypes, validate object keys, avoid recursive merging of untrusted data.
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External POC / Exploit Code
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