CVE-2026-56672 – ComfyUI: Stored XSS via /userdata/{file} due to Missing Content-Type Sanitization

CVE ID :CVE-2026-56672

Published : July 31, 2026, 4:27 a.m. | 1 hour, 19 minutes ago

Description :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.

Severity: 0.0 | NA

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