id: PYSEC-2026-1699
published: "2026-07-07T16:03:06.332347Z"
modified: "2026-07-07T17:24:49.177855Z"
aliases:
- CVE-2025-53354
- GHSA-8c95-hpq2-w46f
summary: NiceGUI has a Reflected XSS
details: "### Summary\n\nA Cross-Site Scripting (XSS) risk exists in NiceGUI when developers render unescaped user input into the DOM using `ui.html()`. Before version 3.0, NiceGUI does not enforce HTML or JavaScript sanitization, so applications that directly combine components like `ui.input()` with `ui.html()` without escaping may allow attackers to execute arbitrary JavaScript in the user’s browser. Same holds for `ui.chat_message` with HTML content.\n\nApplications that directly reflect user input via `ui.html()` (or `ui.chat_message` in HTML mode) are affected. This may lead to client-side code execution (e.g., session hijacking or phishing). Applications that do not pass untrusted input into ui.html() are not affected.\n\n### Details\n\nNiceGUI allows developers to bind user input directly into the DOM using `ui.html()` or `ui.chat_message()`. However, the library does not enforce any HTML or JavaScript sanitization, which potentially creates a dangerous attack surface for developers unaware of this behavior.\n\nThe vulnerable code path appears when combining these:\n\n```python\nui.input(\"XSS Input:\", on_change=inject)\ndef inject(e):\n    ui.html(f'{e.value}')\n```\n\nIn this setup, any input provided by the user is rendered **verbatim** into the page’s DOM via innerHTML, enabling injection of script-based payloads.\n\n### PoC (Proof of Concept)\n\n1. Create a simple app:\n\n   ```python\n   from nicegui import ui\n\n   @ui.page('/')\n   def main():\n       def inject(e):\n           ui.html(f'{e.value}')  # vulnerable use\n\n       ui.input(\"XSS Input:\", on_change=inject)\n\n   ui.run()\n   ```\n\n2. Run the app:\n\n   ```bash\n   python app.py\n   ```\n\n3. In the browser, input the following payload:\n\n   ```html\n   <img src=x onerror=alert('XSS')>\n   ```\n\n4. Observe the JavaScript alert popup:\n\n   ```\n   XSS\n   ```\n\n### Impact\n\n* **Vulnerability type:** Reflected Cross-Site Scripting (XSS)\n* **Attack vector:** User input rendered as raw HTML\n* **Affected users:** Any NiceGUI-based application using `ui.html()` or `ui.chat_message()` with HTML content from user input"
affected:
- package:
    name: nicegui
    ecosystem: PyPI
    purl: pkg:pypi/nicegui
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - fixed: 3.0.0
  versions:
  - 0.1.0
  - 0.1.4
  - 0.1.6
  - 0.2.0
  - 0.2.1
  - 0.2.10
  - 0.2.11
  - 0.2.12
  - 0.2.13
  - 0.2.14
  - 0.2.15
  - 0.2.2
  - 0.2.3
  - 0.2.4
  - 0.2.9
  - 0.3.0
  - 0.3.1
  - 0.3.2
  - 0.3.3
  - 0.3.4
  - 0.3.5
  - 0.3.6
  - 0.3.7
  - 0.3.8
  - 0.3.9
  - 0.4.0
  - 0.4.1
  - 0.4.10
  - 0.4.11
  - 0.4.12
  - 0.4.13
  - 0.4.14
  - 0.4.15
  - 0.4.2
  - 0.4.3
  - 0.4.4
  - 0.4.5
  - 0.4.6
  - 0.4.7
  - 0.4.8
  - 0.4.9
  - 0.5.0
  - 0.5.1
  - 0.5.10
  - 0.5.11
  - 0.5.12
  - 0.5.2
  - 0.5.3
  - 0.5.4
  - 0.5.5
  - 0.5.6
  - 0.5.7
  - 0.5.8
  - 0.5.9
  - 0.6.0
  - 0.6.1
  - 0.6.10
  - 0.6.11
  - 0.6.12
  - 0.6.13
  - 0.6.2
  - 0.6.3
  - 0.6.4
  - 0.6.5
  - 0.6.6
  - 0.6.7
  - 0.6.8
  - 0.6.9
  - 0.7.0
  - 0.7.1
  - 0.7.10
  - 0.7.11
  - 0.7.12
  - 0.7.13
  - 0.7.14
  - 0.7.15
  - 0.7.16
  - 0.7.17
  - 0.7.18
  - 0.7.19
  - 0.7.2
  - 0.7.21
  - 0.7.22
  - 0.7.23
  - 0.7.24
  - 0.7.25
  - 0.7.26
  - 0.7.27
  - 0.7.28
  - 0.7.29
  - 0.7.3
  - 0.7.30
  - 0.7.4
  - 0.7.6
  - 0.7.7
  - 0.7.8
  - 0.7.9
  - 0.8.0
  - 0.8.1
  - 0.8.10
  - 0.8.11
  - 0.8.12
  - 0.8.13
  - 0.8.14
  - 0.8.15
  - 0.8.16
  - 0.8.2
  - 0.8.3
  - 0.8.4
  - 0.8.5
  - 0.8.6
  - 0.8.7
  - 0.8.8
  - 0.8.9
  - 0.9.0
  - 0.9.1
  - 0.9.10
  - 0.9.11
  - 0.9.12
  - 0.9.13
  - 0.9.14
  - 0.9.15
  - 0.9.16
  - 0.9.17
  - 0.9.18
  - 0.9.19
  - 0.9.2
  - 0.9.20
  - 0.9.21
  - 0.9.22
  - 0.9.23
  - 0.9.24
  - 0.9.25
  - 0.9.26
  - 0.9.27
  - 0.9.28
  - 0.9.3
  - 0.9.4
  - 0.9.5
  - 0.9.6
  - 0.9.7
  - 0.9.8
  - 0.9.9
  - 1.0.1
  - 1.0.10
  - 1.0.2
  - 1.0.3
  - 1.0.4
  - 1.0.5
  - 1.0.6
  - 1.0.7
  - 1.0.8
  - 1.0.9
  - 1.1.0
  - 1.1.1
  - 1.1.10
  - 1.1.11
  - 1.1.2
  - 1.1.3
  - 1.1.4
  - 1.1.5
  - 1.1.6
  - 1.1.7
  - 1.1.8
  - 1.1.9
  - 1.2.0
  - 1.2.1
  - 1.2.10
  - 1.2.11
  - 1.2.12
  - 1.2.13
  - 1.2.14
  - 1.2.15
  - 1.2.16
  - 1.2.17
  - 1.2.18
  - 1.2.2
  - 1.2.20
  - 1.2.21
  - 1.2.22
  - 1.2.23
  - 1.2.24
  - 1.2.3
  - 1.2.4
  - 1.2.5
  - 1.2.6
  - 1.2.7
  - 1.2.8
  - 1.2.9
  - 1.3.0
  - 1.3.1
  - 1.3.10
  - 1.3.11
  - 1.3.12
  - 1.3.13
  - 1.3.14
  - 1.3.15
  - 1.3.16
  - 1.3.17
  - 1.3.18
  - 1.3.2
  - 1.3.3
  - 1.3.4
  - 1.3.5
  - 1.3.6
  - 1.3.7
  - 1.3.8
  - 1.3.9
  - 1.4.0
  - 1.4.1
  - 1.4.10
  - 1.4.11
  - 1.4.12
  - 1.4.13
  - 1.4.14
  - 1.4.15
  - 1.4.16
  - 1.4.17
  - 1.4.18
  - 1.4.19
  - 1.4.2
  - 1.4.20
  - 1.4.21
  - 1.4.22
  - 1.4.23
  - 1.4.24
  - 1.4.25
  - 1.4.26
  - 1.4.27
  - 1.4.28
  - 1.4.29
  - 1.4.3
  - 1.4.30
  - 1.4.31
  - 1.4.33
  - 1.4.34
  - 1.4.35
  - 1.4.36
  - 1.4.37
  - 1.4.4
  - 1.4.5
  - 1.4.6
  - 1.4.7
  - 1.4.8
  - 1.4.9
  - 2.0.0
  - 2.0.1
  - 2.1.0
  - 2.10.0
  - 2.10.1
  - 2.11.0
  - 2.11.1
  - 2.12.0
  - 2.12.1
  - 2.13.0
  - 2.14.0
  - 2.14.1
  - 2.15.0
  - 2.16.0
  - 2.16.1
  - 2.17.0
  - 2.18.0
  - 2.19.0
  - 2.2.0
  - 2.20.0
  - 2.21.0
  - 2.21.1
  - 2.22.0
  - 2.22.1
  - 2.22.2
  - 2.23.0
  - 2.23.1
  - 2.23.2
  - 2.23.3
  - 2.24.0
  - 2.24.1
  - 2.24.2
  - 2.3.0
  - 2.4.0
  - 2.5.0
  - 2.7.0
  - 2.8.0
  - 2.8.1
  - 2.9.0
  - 2.9.1
  - 3.0.0rc1
references:
- type: WEB
  url: https://github.com/zauberzeug/nicegui/security/advisories/GHSA-8c95-hpq2-w46f
- type: ADVISORY
  url: https://nvd.nist.gov/vuln/detail/CVE-2025-53354
- type: WEB
  url: https://github.com/zauberzeug/nicegui/commit/4673dc35c94a0c7339e2164378b0977332e60775
- type: PACKAGE
  url: https://github.com/zauberzeug/nicegui
- type: PACKAGE
  url: https://pypi.org/project/nicegui
- type: ADVISORY
  url: https://github.com/advisories/GHSA-8c95-hpq2-w46f
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N