HeyForm Vulnerable to Stored XSS via Unauthenticated SVG File Upload

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Summary

CVECVE-2026-45797
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-20 16:17:00 UTC
Updated2026-07-20 19:17:23 UTC
DescriptionHeyForm 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.

Risk And Classification

Primary CVSS: v4.0 6.4 MEDIUM from [email protected]

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-79 | CWE-434 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | CWE-434 CWE-434: Unrestricted Upload of File with Dangerous Type

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.4MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/C...
4.0CNADECLARED6.4MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
High
Sub Integrity
High
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Heyform Heyform affected < 3.0.0-rc.7 Not specified

References

ReferenceSourceLinkTags
github.com/heyform/heyform/commit/144240e5545d10fd9e120d05ccb402a6d7064674 [email protected] github.com
github.com/heyform/heyform/security/advisories/GHSA-m94h-jxvc-hhch [email protected] github.com
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