CVE-2026-39844 — MEDIUM (5.9)

Q: How severe is CVE-2026-39844?

CVE-2026-39844 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.

Q: Is there a patch for CVE-2026-39844?

Check the references section above for vendor advisories and patch information. Affected products include: Zauberzeug Nicegui, Microsoft Windows.

Vulnerability Description

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.

CVSS Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

HIGH

Availability

NONE

Affected Products

Vendor	Product	Versions
Zauberzeug	Nicegui	< 3.10.0
Microsoft	Windows	-

Related Weaknesses (CWE)

CWE-22

References

FAQ

What is CVE-2026-39844?

CVE-2026-39844 is a vulnerability with a CVSS score of 5.9 (MEDIUM). 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 backsl...

How severe is CVE-2026-39844?

CVE-2026-39844 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-39844?

Check the references section above for vendor advisories and patch information. Affected products include: Zauberzeug Nicegui, Microsoft Windows.