CVE-2026-27199

MEDIUM EPSS 42.2%
Published Feb 21, 20264mo ago · Modified Mar 3, 20264mo ago
6.3 CVSS 4.0
Medium
Find Similar
Published Feb 21, 2026 4mo ago
Last Modified Mar 3, 2026 4mo ago

Description

Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.

CVSS Details

Base Score
6.3
Exploitability
—
Impact
—
Vector string
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
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
42.2% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-67

Affected Products 1

VendorProductVersionRange
palletsprojectswerkzeug* <3.1.6

References 3

  • github.com https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d
    Patch
  • github.com https://github.com/pallets/werkzeug/releases/tag/3.1.6
    Release Notes
  • github.com https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6x
    Vendor Advisory

Remediation

  • github.com https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d
    Patch