CVE-2025-66221
5.3 · MEDIUMOverview
CVE-2025-66221 is a medium-severity vulnerability affecting palletsprojects werkzeug. It was published on November 29, 2025 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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 implicitly present and readable in every directory. send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been patched in version 3.1.4.
Remediation
Check the references section for vendor advisories and patches from palletsprojects. Update werkzeug to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| palletsprojects | werkzeug | >= 0, < 3.1.4 | Affected |
Frequently Asked Questions
What is CVE-2025-66221?
CVE-2025-66221 is a medium-severity vulnerability affecting palletsprojects werkzeug. It was published on November 29, 2025 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
How severe is CVE-2025-66221?
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2025-66221?
Check the references section for vendor advisories and patches from palletsprojects. Update werkzeug to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-66221?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-66221 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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