PT-2026-21351 · Werkzeug · Werkzeug

Alimezar · CVE-2026-27199 · Published 2026-02-19 · Updated 2026-07-21

Positive Technologies (AI Summary)

CVSS v4.0

6.3

Medium

Base vector

AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Name of the Vulnerable Software and Affected Versions Werkzeug versions 3.1.5 and below

Description The safe join function in Werkzeug, a WSGI web application library, improperly handles Windows device names when used as filenames, particularly when preceded by other path segments. Specifically, the function allows Windows device names as filenames, potentially leading to indefinite hanging when reading files if the application is running on Windows and the requested path ends with a special device name. The send from directory function utilizes safe join to serve files, making it susceptible to this issue.

Recommendations Update to Werkzeug version 3.1.6 or later.

Exploit

Fix

Weakness Enumeration

CWE-67

Related Identifiers

CLEANSTART-2026-AZ09261

CLEANSTART-2026-HP19968

CLEANSTART-2026-IR98353

CLEANSTART-2026-MR94452

CLEANSTART-2026-NL78203

CLEANSTART-2026-WQ85001

CLEANSTART-2026-WU03167

CVE-2026-27199

GHSA-29VQ-49WR-VM6X

PYSEC-2026-2320

Affected Products

Werkzeug

References · 198

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27199.json · Exploit
• https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6x · Vendor Advisory
• https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d · Patch
• https://osv.dev/vulnerability/CLEANSTART-2026-AZ09261 · Vendor Advisory
• https://osv.dev/vulnerability/CLEANSTART-2026-NL78203 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-34073 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-26007 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-45186 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2025-62727 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2024-49766 · Security Note
• https://osv.dev/vulnerability/ALPINE-CVE-2026-27199 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-25645 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-48710 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2024-34069 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-31958 · Security Note