Is CVE-2026-39844 in the CISA KEV catalog?

No. CVE-2026-39844 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-39844?

CVE-2026-39844 has a CVSS v3 base score of 5.9 (MEDIUM).

What is the EPSS score for CVE-2026-39844?

CVE-2026-39844 has an EPSS score of 0.37% (29th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-39844?

Upgrade nicegui to 3.10.0 or later.

CVE & CISA-KEV Catalog

CVE-2026-39844

MEDIUM

5.9

CVSS v3

NVD

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.

CWE-22Path Traversal

How to fix

Remediation Available

niceguiNVD

Affected:< 3.10.0Fixed in:3.10.0CVE-2026-39844derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-22 (Path Traversal) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-23897	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-32315	High	8.6	100%	KEV	Fix
CVE-2022-29464	Critical	9.8	100%	KEV + Ransom	-
CVE-2021-26086	Medium	5.3	100%	KEV	Fix
CVE-2021-22005	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-5902	Critical	9.8	100%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-15.