Comfy-Org ComfyUI up to 0.27.x User Data web.FileResponse path cross site scripting

Summaryinfo

A vulnerability was found in Comfy-Org ComfyUI up to 0.27.x. It has been classified as problematic. Impacted is the function web.FileResponse of the component User Data Handler. Performing a manipulation of the argument path results in cross site scripting. This vulnerability is known as CVE-2026-56672. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Comfy-Org ComfyUI up to 0.27.x. This affects the function web.FileResponse of the component User Data Handler. The manipulation of the argument path with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-56672 since 06/22/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 0.28.0 eliminates this vulnerability.

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Productinfo

Vendor

• Comfy-Org

Name

• ComfyUI

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27

Website

• Product: https://github.com/Comfy-Org/ComfyUI/

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