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npm package

defu

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1 actionable advisory, newest first. Withdrawn advisories and news are excluded. Coverage is partial.

  1. High, CVSS 7.5npmAmendedPublished

    defu: Prototype pollution via __proto__ key in defaults argument

    CVE-2026-35209 · GHSA-737v-mqg7-c878

    Affected
    • npm defu <= 6.1.4
    Fixed in
    6.1.5· Vendor fix available
    Issue
    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: 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

    Recommended action: Upgrade to 6.1.5 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.

    Sources:osv.dev (1)github.com (2)Source checked Evidence →