What is CVE-2025-66221?

CVE-2025-66221 is a medium-severity vulnerability in Microsoft Windows, classified under CWE-67. CVSS score: 5.3/10. Published 2025-11-29.

How severe is CVE-2025-66221?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Microsoft Windows

CVE-2025-66221

Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are impli…

EPSS: 0.005 (38.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Weakness classification (CWE)

CWE-67

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2025-66221?: CVE-2025-66221 is a medium-severity vulnerability in Microsoft Windows, classified under CWE-67. CVSS score: 5.3/10. Published 2025-11-29.
How severe is CVE-2025-66221?: Medium severity. CVSS v3 base score is 5.3 out of 10.