HeyForm is an open-source form builder. Prior to 3.0.1, /api/upload accepts a file according to the client-controlled multipart file.mimetype while retaining an HTML filename, and static/upload serves the resulting file as text/html with contentSecurityPolicy: false. An ordinary user can therefore upload active HTML that executes on the HeyForm origin when a victim opens its returned URL. The same-origin script can access /graphql with the victim's session and read or modify data available to that account. The code also permits upload requests tied to an active public form through formId, openToken, and a fieldId belonging to a file or signature question, although the advisory did not fully verify that unauthenticated path end to end. This issue is fixed in version 3.0.1.
History

Thu, 05 Nov 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Heyform
Heyform heyform
Vendors & Products Heyform
Heyform heyform

Thu, 05 Nov 2026 15:45:00 +0000

Type Values Removed Values Added
Description HeyForm is an open-source form builder. Prior to 3.0.1, /api/upload accepts a file according to the client-controlled multipart file.mimetype while retaining an HTML filename, and static/upload serves the resulting file as text/html with contentSecurityPolicy: false. An ordinary user can therefore upload active HTML that executes on the HeyForm origin when a victim opens its returned URL. The same-origin script can access /graphql with the victim's session and read or modify data available to that account. The code also permits upload requests tied to an active public form through formId, openToken, and a fieldId belonging to a file or signature question, although the advisory did not fully verify that unauthenticated path end to end. This issue is fixed in version 3.0.1.
Title HeyForm: Uploaded HTML files are served as text/html on the app origin with no CSP — stored XSS
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 7.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-11-05T15:32:30.406Z

Updated: 2026-11-05T15:32:30.406Z

Reserved: 2026-09-29T14:18:02.921Z

Link: CVE-2026-102615

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-11-05T16:17:23.937

Modified: 2026-11-05T16:17:24.093

Link: CVE-2026-102615

cve-icon Redhat

No data.