Withdrawn by the publisher.

Affected: CleanStart: renovate

Multiple security vulnerabilities affect the renovate package. These issues are resolved in later releases. See references for individual vulnerability details.

defu is software that allows uers to assign default properties recursively. Prior to version 6.1.5, applications that pass unsanitized user input (e.g. parsed JSON request bodies, database records, or config files from untrusted sources) as the first argument to `defu()` are vulnerable to prototype pollution. A crafted payload containing a `__proto__` key can override intended default values in the merged resul. The internal `_defu` function used `Object.assign({}, defaults)` to copy the defaults object. `Object.assign` invokes the `__proto__` setter, which replaces the resulting object's `[[Prototype]]` with attacker-controlled values. Properties inherited from the polluted prototype then bypass the existing `__proto__` key guard in the `for...in` loop and land in the final result. Version 6.1.5 replaces `Object.assign({}, defaults)` with object spread (`{ ...defaults }`), which uses `[[DefineOwnProperty]]` and does not invoke the `__proto__` setter.

Affected: npm: defu

### Impact

Applications that pass unsanitized user input (e.g. parsed JSON request bodies, database records, or config files from untrusted sources) as the first argument to `defu()` are vulnerable to prototype pollution.

A crafted payload containing a `__proto__` key can override intended default values in the merged result:

```js import { defu } from 'defu'

const userInput = JSON.parse('{"__proto__":{"isAdmin":true}}') const config = defu(userInput, { isAdmin: false })

config.isAdmin // true — attacker overrides the server default ```

### Root Cause

The internal `_defu` function used `Object.assign({}, defaults)` to copy the defaults object. `Object.assign` invokes the `__proto__` setter, which replaces the resulting object's `[[Prototype]]` with attacker-controlled values. Properties inherited from the polluted prototype then bypass the existing `__proto__` key guard in the `for...in` loop and land in the final result.

### Fix

Replace `Object.assign({}, defaults)` with object spread (`{ ...defaults }`), which uses `[[DefineOwnProperty]]` and does not invoke the `__proto__` setter.

### Affected Versions

<= 6.1.4

### Credits

Reported by [@BlackHatExploitation](https://github.com/BlackHatExploitation)