CVE-2026-102615
HeyForm is an open-source form builder. Prior to 3.0.1, /api/upload accepts a file according to the client-controlled multipart file.mimetyp
CVSS
7.6
High
EPSS
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KEV
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Exploit Today
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0-100
Published: Nov 5, 2026 · Last modified: Nov 5, 2026 · CWE-79
Not enough EPSS history yet.
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.