CVE-2026-92781Public exploitNetwork attack vector

Browser prototype pollution via unguarded unflatten paths

Published Sep 16, 2026 · Updated Sep 21, 2026

Prototype pollution in Builder.io Gen2 SDKs through 5.2.11 and 0.25.13 allows remote attackers to alter browser objects via preview links. The unflatten helper splits builder.userAttributes dotted keys and assigns each segment without rejecting proto, prototype, or constructor, so a crafted preview URL writes into Object.prototype. A visitor must open the link; the pollution remains within that browser context and changes properties inherited by unrelated objects.

CVSS severity5.3

Medium

EPSS probability0.36%

Next 30 days · Oct 19, 2026

Known exploitationUnconfirmed

Based on sourced intelligence

Hinoki checkNot available

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Summary

What happened

The record

CVE: CVE-2026-92781
Published: Sep 16, 2026
Updated: Sep 21, 2026

Vendor: Builder.io
Product: @builder.io/sdk-solid
Classifications: CWE-1321, CAPEC-1, CAPEC-77, CAPEC-180, T1204.001

Attack vector: network
Privileges: unauthenticated

Timeline

How it unfolded

Sep 16, 2026CVE publishedPublication date reported by the CVE source.
Sep 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

Affected versionversion=0 <=5.2.11

What conditions does exploitation require?

Attack vectornetwork

Required privilegesunauthenticated

What is affected?

Builder.io · @builder.io/sdk-solidversion=0 <=5.2.11

Builder.io · @builder.io/sdk-svelteversion=0 <=5.2.11

Builder.io · @builder.io/sdk-angularversion=0 <=0.25.13

Builder.io · @builder.io/sdk-qwikversion=0 <=0.25.13

Builder.io · @builder.io/sdk-vueversion=0 <=5.2.11

Builder.io · @builder.io/sdk-reactversion=0 <=5.2.11

Builder.io · @builder.io/sdk-react-nextjsversion=0 <=0.25.13

Published CVSS scores

6.3VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

5.3VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026

Latest reporting daySep 28, 2026

Latest daily unique IPsUnavailable

Prior 30-day averageUnavailable

SourceShadowserver honeypots (KEV)

Vectornetwork

Privilegesunauthenticated

Known exploitationUnconfirmed

Public exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

CAPEC-1Accessing Functionality Not Properly Constrained by ACLs

CAPEC-77Manipulating User-Controlled Variables

CAPEC-180Exploiting Incorrectly Configured Access Control Security Levels

T1204.001User Execution: Malicious Link

Public exploit references

Reflected client-side prototype pollution preview-link proof of conceptproof of concept · demonstrated

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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