Skip to content
Fencer Vulns
critical 9.0

CVE-2026-35198 json

HeyForm vulnerable to stored XSS via form field titles

published 2026-07-20 3 mo ago modified 2026-08-21 2 mo ago also EUVD-2026-45984

cvss
9.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

HeyForm is an open-source form builder. Prior to version 3.0.0-rc.7, a stored cross-site scripting (XSS) vulnerability in the form builder allows a low-privileged team member to inject malicious JavaScript that executes when a team owner views the form, leading to complete account takeover through privilege escalation. Version 3.0.0-rc.7 contains a patch for the issue.

Patch / fix

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
3 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/heyform/heyform/security/advisories/GHSA-chmm-jqpm-3pwx referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Affected products

  • heyform heyform

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.