Is CVE-2026-21860 actively exploited?

CVE-2026-21860 has no public evidence of in-the-wild exploitation as of 2026-02-02.

What is the CVSS score for CVE-2026-21860?

CVE-2026-21860 has a CVSS score of 6.3 (MEDIUM severity). Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

How do I patch CVE-2026-21860?

Patch guidance is available from palletsprojects security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-21860.

Which products are affected by CVE-2026-21860?

1 product: palletsprojects werkzeug.

CVE-2026-21860 - remediation guidance & executive summary

Description

Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt, or trailing spaces such as CON. This issue has been patched in version 3.1.5.

CVSS Metrics

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector: network
Complexity: low
Privileges: none
User Action: none
Confidentiality: undefined
Integrity: undefined
Availability: undefined
Weaknesses: CWE-67

Metadata

Primary Vendor: PALLETSPROJECTS
Published: 1/8/2026
Last Modified: 2/2/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

palletsprojects : werkzeug

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-21860. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-21860

View on NIST NVD

CVE-2026-21860 vulnerability