CVE-2026-92781
CVE-2026-92781
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.
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.004 (29.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 29.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Weakness classification (CWE)
References
- github.com/BuilderIO/builder/issues/4824 (issue-tracking)
- github.com/BuilderIO/builder (product)
- github.com/BuilderIO/builder/blob/main/packages/sdks/src/functions/get-content/… (technical-description)
- github.com/BuilderIO/builder/blob/main/packages/sdks/src/helpers/flatten.ts (technical-description)
- www.vulncheck.com/advisories/builder-io-gen2-sdks-through-5.2.11-prototype-poll… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-92781?
- CVE-2026-92781 is a medium-severity vulnerability, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 6.3/10. Published 2026-09-16.
- How severe is CVE-2026-92781?
- Medium severity. CVSS v3 base score is 6.3 out of 10.