CVE-2025-66221
Werkzeug safe_join() allows Windows special device names
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.
INFO
Published Date :
Nov. 29, 2025, 3:16 a.m.
Last Modified :
Dec. 3, 2025, 3:27 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Werkzeug to version 3.1.4.
- Apply necessary patches if updating is not possible.
- Avoid using user-provided paths for file access.
- Sanitize all user inputs before processing.
Public PoC/Exploit Available at Github
CVE-2025-66221 has a 5 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-66221.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-66221 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-66221
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Python
Code to test SAST and SCA Reachability
Python
None
Dockerfile Python HTML
None
Dockerfile Python HTML
Exploit for Werkzeug < 3.1.4 (CVE-2023-46136)
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-66221 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-66221 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Dec. 03, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CPE Configuration AND OR *cpe:2.3:a:palletsprojects:werkzeug:*:*:*:*:*:*:*:* versions up to (excluding) 3.1.4 OR cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Added Reference Type GitHub, Inc.: https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/pallets/werkzeug/releases/tag/3.1.4 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2 Types: Vendor Advisory -
New CVE Received by [email protected]
Nov. 29, 2025
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CWE CWE-67 Added Reference https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13 Added Reference https://github.com/pallets/werkzeug/releases/tag/3.1.4 Added Reference https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2