CVE-2026-56672 Comfy-Org CVE debrief

Who should care

Users of ComfyUI versions prior to 0.28.0, administrators of systems with ComfyUI installed, and security teams monitoring for cross-site scripting vulnerabilities should take immediate action to mitigate this vulnerability. This includes upgrading ComfyUI to version 0.28.0 or later, reviewing and restricting user-uploaded content, and implementing additional security measures for API tokens and settings. Security teams should review compensating controls for exposed systems while remediation is scheduled and verified, and track exceptions, retest remediated assets, and close the item only after evidence is documented. Affected operators and platforms should be identified, and vulnerability management and security teams should be informed to ensure proper mitigation and monitoring of the vulnerability's impact. This vulnerability has a CVSS score of 8.2, indicating high severity, and immediate attention is advised to prevent potential attacks and data breaches. The CVE record was published on 2026-07-31T06:16:30.170Z and has not been modified since then, emphasizing the need for prompt action based on the information provided. Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance, and plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Check relevant monitoring, detection, and logs for exposed assets that need extra review to ensure that potential security incidents are identified and addressed promptly. Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up to ensure accountability and timely remediation. Overall, a comprehensive approach is necessary to address the risks associated with CVE-2026-56672 effectively. This involves not only technical mitigation but also ensuring that all relevant stakeholders are informed and engaged in the remediation process. By taking these steps, organizations can reduce the risk of exploitation and protect their assets from potential attacks. It is essential to prioritize this vulnerability due to its high severity and the potential for significant impact if left unm

Technical summary

CVE-2026-56672 is a stored cross-site scripting vulnerability in ComfyUI's GET /userdata/{file} endpoint. Prior to version 0.28.0, user-controlled HTML and SVG files were served with extension-derived content types, allowing scripts to execute same-origin and access sensitive information. The handler used web.FileResponse(path), serving uploaded .html/.svg files as text/html/image/svg+xml. POST /userdata stored arbitrary request bodies in the user's userdata directory. When a victim navigated to the file URL, the embedded script executed same-origin, potentially accessing browser-stored API tokens, settings, workflows, and authenticated-equivalent API calls.

Defensive priority

CVE-2026-56672 is rated HIGH with a CVSS score of 8.2; immediate attention is advised.

Recommended defensive actions

• Upgrade ComfyUI to version 0.28.0 or later
• Review and restrict user-uploaded content
• Implement additional security measures for API tokens and settings
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE-2026-56672 issue involves stored cross-site scripting via user-controlled HTML and SVG files served by ComfyUI's GET /userdata/{file} endpoint prior to version 0.28.0. The handler used web.FileResponse(path), serving uploaded .html/.svg files as text/html/image/svg+xml. POST /userdata stored arbitrary request bodies in the user's userdata directory. When a victim navigated to the file URL, the embedded script executed same-origin, potentially accessing browser-stored API tokens, settings, workflows, and authenticated-equivalent API calls.

Official resources