CVE-2026-35198Public exploitNetwork attack vector

Account takeover via unsanitized field titles

Published Jul 20, 2026 · Updated Jul 20, 2026

Stored XSS in HeyForm before 3.0.0-rc.7 allows remote authenticated users to take over a team owner's account through a field title. The updateFormSchemas GraphQL mutation stores arbitrary HTML or JavaScript in a field title, and Block.tsx assigns that value to innerHTML without sanitization. A low-privileged team member must share a form with an owner and wait for that owner to open the builder; the script then runs as the owner and can transfer team ownership, read submissions, modify forms, or delete workspace data.

CVSS severity9.0
Critical
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in HeyForm before 3.0.0-rc.7 allows remote authenticated users to take over a team owner's account through a field title. The updateFormSchemas GraphQL mutation stores arbitrary HTML or JavaScript in a field title, and Block.tsx assigns that value to innerHTML without sanitization. A low-privileged team member must share a form with an owner and wait for that owner to open the builder; the script then runs as the owner and can transfer team ownership, read submissions, modify forms, or delete workspace data.

The record

CVE
CVE-2026-35198
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
HeyForm
Product
HeyForm
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 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.

  1. Affected versionversion=< 3.0.0-rc.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

HeyForm · HeyFormversion=< 3.0.0-rc.7

Published CVSS scores

9.0GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

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

Technologies

Your stack

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Your stack

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