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Vulnerabilities

Security fix · CVE-2026-21860

Werkzeug is a comprehensive WSGI web application library.

Published Jan 8, 2026 · catalog updated Jan 8, 2026 · Werkzeug is a comprehensive

Last checked Oct 31, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-21860. EPSS is 0.47%. Act only if a listed version of Werkzeug is a comprehensive is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Werkzeug is a comprehensive).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium6.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.47%
Remediation
Version ranges on file
Affected products
vendor pallets werkzeug < 3.1.5

Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt, or trailing spaces such as CON. This issue has been patched in version 3.1.5.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor pallets werkzeug < 3.1.5< 3.1.5

How to fix CVE-2026-21860

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-21860. EPSS is 0.47%. Act only if a listed version of Werkzeug is a comprehensive is installed.

Which versions are affected?

Compare what you have installed with pallets werkzeug < 3.1.5 < 3.1.5. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.47%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 8, 2026 · EUVD

    Detected

    Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt,

  2. Jan 8, 2026 · EUVD

    Updated

    Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as CON.txt,

Sources

  • CVE.orgVulnerability recordCVE-2026-21860

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-21860

    30-day exploitation probability 0.47%

    first.org
  • EUVDVulnerability recordEUVD-2026-1425

    Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as CON, AUX, etc that are i

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 31, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 31, 2026
  • CVE.orgOct 31, 2026
  • EUVDOct 30, 2026