NiceGUI has a Path Traversal in NiceGUI Upload Filename on Windows via Backslash Bypass of PurePosixPath Sanitization
Priority LOW 33CWE-22Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub.
Summary
NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path separators, an attacker can bypass this sanitization on Windows by using backslashes (\) in the upload filename. Applications that construct file paths using file.name (a pattern demonstrated in NiceGUI's bundled examples) are vulnerable to arbitrary file write on Windows. This vulnerability is fixed in 3.10.0.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00385 32nd percentileScored 2026-11-07
Fix Fixed nicegui (zauberzeug): 3.10.0nicegui (PyPI): 3.10.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| zauberzeug | nicegui | before 3.10.0 | 3.10.0 | Patch available | CNA |
| — | nicegui (PyPI) | before 3.10.0 | 3.10.0 | Patch available | GHSA-w8wv-vfpc-hw2w |
- nicegui Vendorzauberzeug Affected before 3.10.0 Fixed in 3.10.0 Patch available CNA
- nicegui (PyPI) Vendor— Affected before 3.10.0 Fixed in 3.10.0 Patch available GHSA-w8wv-vfpc-hw2w
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:* | before 3.10.0 | Vulnerable | zauberzeug |
| cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Microsoft |
- cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:* Versions before 3.10.0 Vulnerable ·zauberzeug
- cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Microsoft
Remediation
- Fix · CNA nicegui (zauberzeug) Fixed in 3.10.0
- Fix · GHSA-w8wv-vfpc-hw2w nicegui (PyPI) Fixed in 3.10.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-39844
- 2026-10-03 Alias added: GHSA-w8wv-vfpc-hw2w
References
Advisory 2
More zauberzeug Nicegui vulnerabilities
- TI-2025-41029 NiceGUI Path Traversal Vulnerability in app.add_media_files() Allows Arbitrary File Reading CVSS 3.1HIGH 7.5
- TI-2026-17574 Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages` CVSS 3.1HIGH 7.2
- TI-2026-17575 NiceGUI has Redis connection leak via tab storage causes service degradation CVSS 3.1MEDIUM 5.3
- TI-2026-17573 NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links CVSS 3.1MEDIUM 6.1
- TI-2026-17572 NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace() CVSS 3.1MEDIUM 6.1
- TI-2025-40897 NiceGUI Stored/Reflected XSS in ui.interactive_image via unsanitized SVG content CVSS 3.1MEDIUM 6.1
Sources
- CVE-2026-39844 · CVE Program
- CVE-2026-39844 · NVD
- FIRST EPSS
- GHSA-w8wv-vfpc-hw2w · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences