Security vulnerabilities and automated fixes for prototype pollution issues
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A high-severity prototype pollution vulnerability (CVE-2026-35209) was discovered in the `defu` package version 6.1.4, which allowed attackers to inject properties into JavaScript's `Object.prototype` via the `__proto__` key in defaults arguments. The fix upgrades `defu` to version 6.1.5 in the frontend's dependency tree, protecting downstream consumers like `c12` and `dotenv` configuration loaders from malicious property injection.
CVE-2026-35209 is a high-severity prototype pollution vulnerability in the `defu` JavaScript library (versions prior to 6.1.5) that allows attackers to inject arbitrary properties onto `Object.prototype` by passing a `__proto__` key in the defaults argument. The vulnerability was present in the `blog-site` project's dependency tree and was resolved by upgrading `defu` to 6.1.5 and adding an explicit `overrides` entry to prevent transitive re-introduction of the vulnerable version.