---
id: CVE-2026-56672
title: 'ComfyUI is a node-based diffusion model GUI, API, and backend'
summary: >-
  ComfyUI is a node-based diffusion model GUI, API, and backend. Prior to
  0.28.0, GET /userdata/{file} served user-controlled HTML and SVG files with
  extension-derived content types, allowing stored cross-site scripting in the
  ComfyUI orig…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N'
cwe:
  - CWE-79
published: '2026-07-31'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:41:31.497'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-56672'
references:
  - url: >-
      https://github.com/Comfy-Org/ComfyUI/commit/96e0e3585b41e1417442eaa14ec57f7b4ffcb5e0
    label: security-advisories@github.com
  - url: 'https://github.com/Comfy-Org/ComfyUI/releases/tag/v0.28.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/Comfy-Org/ComfyUI/security/advisories/GHSA-53g8-45wq-pcv8
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00397
epssPercentile: 0.31039
ingestedAt: '2026-09-08T21:11:12.260Z'
---

## Overview

ComfyUI is a node-based diffusion model GUI, API, and backend. Prior to 0.28.0, GET /userdata/{file} served user-controlled HTML and SVG files with extension-derived content types, allowing stored cross-site scripting in the ComfyUI origin and access to browser-stored API tokens, settings, workflows, and authenticated-equivalent API calls. The handler used web.FileResponse(path), so an uploaded .html/.svg was served as text/html/image/svg+xml. POST /userdata stores arbitrary request bodies (confined to the user's userdata directory). When a victim navigated to the file URL, the embedded script executed same-origin. The /view endpoint already forced dangerous MIME types to download; that protection had never been applied to /userdata. This issue is fixed in version 0.28.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.