XSS in Comfy-Org Comfyui
CVE-2026-56672
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.002 (14.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N.
Affected products
- Comfy-org Comfyui — versions < 0.28.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-56672?
- CVE-2026-56672 is a high-severity vulnerability in Comfy-Org Comfyui, classified under Cross-site Scripting. CVSS score: 8.2/10. Published 2026-07-31.
- How severe is CVE-2026-56672?
- High severity. CVSS v3 base score is 8.2 out of 10.