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TI-2026-33532 Aliases CVE-2026-45797

HeyForm Vulnerable to Stored XSS via Unauthenticated SVG File Upload

Priority LOW 35CWE-434Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Code execution, Cross-site scripting
Confidentiality · integrity · availability
None · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-434 and CWE-79.

Summary

HeyForm is an open-source form builder. Prior to version 3.0.0-rc.7, the `/api/upload` endpoint allows unauthenticated file uploads including SVG files. Uploaded SVGs are stored in the static assets directory and served with `Content-Type: image/svg+xml` by Express's serve-static middleware, allowing an attacker to achieve stored cross-site scripting (XSS) on the heyform domain without any authentication. Version 3.0.0-rc.7 contains a patch for the issue.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0057 47th percentileScored 2026-11-07
Fix Fixed heyform (heyform): 3.0.0-rc.7

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
heyformheyformbefore 3.0.0-rc.73.0.0-rc.7Patch availableCNA
  • heyform Vendorheyform Affected before 3.0.0-rc.7 Fixed in 3.0.0-rc.7 Patch available CNA

Remediation

  • Fix · CNA heyform (heyform) Fixed in 3.0.0-rc.7

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45797

References

Other 2

  • TI-2026-45208 HeyForm has unauthenticated /api/upload endpoint that accepts arbitrary files with no auth/session/form context CVSS 3.1HIGH 8.6
  • TI-2026-27351 HeyForm vulnerable to stored XSS via form field titles CVSS 3.1CRITICAL 9.0
  • TI-2026-56756 HeyForm Reflects Any Origin in CORS Responses While Allowing Credentials CVSS 3.1HIGH 8.1
  • TI-2026-45207 Improper input validation in heyform CVSS 3.1MEDIUM 5.8
  • TI-2026-85482 Stored cross-site scripting in HeyForm via uploaded HTML files CVSS 3.1HIGH 7.6

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences