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

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-56672
Confirmed fixed CVEs
Not specified
Updated in this feed
7 Nov 2026, 03:19 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 31 Jul 2026, 04:27 UTC

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.

osv:CVE-2026-56672
Complete source record
{
  "id": "45d9c82576bc968c4c333a1a0f5fa618dad4042457d94bc33ceb29f8972d49d1",
  "url": "https://osv.dev/vulnerability/CVE-2026-56672",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ComfyUI: Stored XSS via /userdata/{file} due to Missing Content-Type Sanitization",
    "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 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.",
    "evidence": "osv:CVE-2026-56672",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-56672",
      "aliases": [
        "CVE-2026-56672",
        "GHSA-53g8-45wq-pcv8"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/comfy-org/comfyui",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "700821e1364eaab0e8f21c538a2131719fec57bf"
                },
                {
                  "fixed": "96e0e3585b41e1417442eaa14ec57f7b4ffcb5e0"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.28.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "96e0e3585b41e1417442eaa14ec57f7b4ffcb5e0"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "700821e1364eaab0e8f21c538a2131719fec57bf"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.28.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.27.0",
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            "latest"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56672.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.355327734Z",
      "provider": "osv",
      "references": [
        "https://github.com/Comfy-Org/ComfyUI/releases/tag/v0.28.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56672.json",
        "https://github.com/Comfy-Org/ComfyUI/security/advisories/GHSA-53g8-45wq-pcv8",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-56672",
        "https://github.com/Comfy-Org/ComfyUI/commit/96e0e3585b41e1417442eaa14ec57f7b4ffcb5e0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56672.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-56672",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517699,
  "published_at": "2026-07-31T04:27:18.721+00:00"
}