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Medium · 6.3 CVE-2026-92781 EUVD-2026-81044GHSA-mgr8-fxxv-82mj

Builder.io Gen2 SDKs through 5.2.11 Prototype Pollution via builder.userAttributes

Published Sep 16, 2026 · Updated Sep 21, 2026 · Assigned by VulnCheck

Description

Builder.io Gen2 SDKs through versions 5.2.11 and 0.25.13 contain a prototype pollution vulnerability in the unflatten helper that processes builder.userAttributes query parameters without prototype guards. Attackers can craft preview links with __proto__ or prototype segments to pollute Object.prototype in a visitor's browser when the SDK processes the malicious URL.

Affected products

VendorProductAffectedFixed
BuilderIO @builder.io/sdk-react ≤ 5.2.11 —
BuilderIO @builder.io/sdk-vue ≤ 5.2.11 —
BuilderIO @builder.io/sdk-svelte ≤ 5.2.11 —
BuilderIO @builder.io/sdk-solid ≤ 5.2.11 —
BuilderIO @builder.io/sdk-qwik ≤ 0.25.13 —
BuilderIO @builder.io/sdk-angular ≤ 0.25.13 —
BuilderIO @builder.io/sdk-react-nextjs ≤ 0.25.13 —

References