# CVE-2026-33332: NiceGUI's unvalidated chunk size parameter in media routes can cause memory exhaustion

Source: https://junglewise.ai/threats/cve-2026-33332-nicegui-s-unvalidated-chunk-size-parameter-in-media-routes-can  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-24  
License: CC BY 4.0 with a link back

CVE-2026-33332 · Severity: low · CVSS 3.1 · Published 2026-03-24

NiceGUI is a Python-based UI framework. Prior to version 3.9.0, NiceGUI's app.add_media_file() and app.add_media_files() media routes accept a user-controlled query parameter that influences how files are read during streaming. The parameter is passed to the range-response implementation without validation, allowing an attacker to bypass chunked streaming and force the server to load entire files into memory at once. With large media files and concurrent requests, this can lead to excessive memory consumption, degraded performance, or denial of service. This issue has been patched in version 3.9.0.

Technologies: [nicegui (PyPI)](https://junglewise.ai/threats/technologies/nicegui). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-33332 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33332 being exploited in the wild.

**How severe is CVE-2026-33332?** Low severity, with a CVSS score of 3.1, published 24 March 2026.

**Which products and versions are affected?** nicegui (PyPI) ECOSYSTEM:introduced=0,fixed=3.9.0.

**Is there a fix for CVE-2026-33332?** Yes. nicegui (PyPI): upgrade to 3.9.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-33332?** Check whether you run nicegui (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- nicegui (PyPI): upgrade to 3.9.0 or later

  ```sh
  pip install "nicegui>=3.9.0"
  ```


## Affected products

- nicegui (PyPI) ECOSYSTEM:introduced=0,fixed=3.9.0

## Identifiers

- CVE-2026-33332
- GHSA-w5g8-5849-vj76
- PYSEC-2026-2233

## Related threats

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- [PYSEC-2026-1702 - NiceGUI apps which use `ui.sub_pages` vulnerable to zero-click XSS](https://junglewise.ai/threats/cve-2026-21873-nicegui-apps-which-use-ui-sub-pages-vulnerable-to-zero-click-xss)
- [PYSEC-2026-1701 - NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links](https://junglewise.ai/threats/cve-2026-21872-nicegui-apps-are-vulnerable-to-xss-which-uses-ui-sub-pages-and)
- [PYSEC-2026-1698 - NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()](https://junglewise.ai/threats/cve-2026-21871-nicegui-is-vulnerable-to-xss-via-unescaped-url-in-ui-navigate)
- [PYSEC-2026-1697 - NiceGUI Reflected XSS in ui.add_css, ui.add_scss, and ui.add_sass via Style Injection](https://junglewise.ai/threats/cve-2025-66469-nicegui-reflected-xss-in-ui-add-css-ui-add-scss-and-ui-add-sass)