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Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in js-yaml

CVE-2025-64718

  • js-yaml
  • org.webjars:js-yaml
  • org.webjars.npm:js-yaml
Medium
5.3/10

Summary

js-yaml is a JavaScript YAML parser and dumper. In js-yaml versions through 3.14.1 and 4.x through 4.1.0, 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 3.14.2 and 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).

  • LOW
  • NETWORK
  • LOW
  • UNCHANGED
  • NONE
  • NONE
  • NONE
  • NONE

CWE-1321 - Prototype Pollution

Prototype pollution is one of the lesser-known vulnerabilities. It allows attackers to abuse the rules of JavaScript by injecting properties into the general object “Object” in JS. Modifying the prototype of “Object” affects the behavior of all objects in the entire app, potentially resulting in denial of service, arbitrary code execution, cross-site scripting, etc.

References

Advisory Timeline

  • Published