GHSA-87hc-h4r5-73f7

Suggest an improvement
Source
https://github.com/advisories/GHSA-87hc-h4r5-73f7
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/01/GHSA-87hc-h4r5-73f7/GHSA-87hc-h4r5-73f7.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-87hc-h4r5-73f7
Aliases
Downstream
Published
2026-01-08T19:51:21Z
Modified
2026-01-08T22:01:40.408683Z
Severity
  • 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
Werkzeug safe_join() allows Windows special device names with compound extensions
Details

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 was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the fix failed to account for compound extensions such as CON.txt.html or trailing spaces. It also missed some additional special names.

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.

Database specific 
{
    "cwe_ids": [
        "CWE-67"
    ],
    "severity": "MODERATE",
    "nvd_published_at": "2026-01-08T19:15:59Z",
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-08T19:51:21Z"
}
References

Affected packages

PyPI / werkzeug

Package

Name
werkzeug
View open source insights on deps.dev
Purl
pkg:pypi/werkzeug

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3.1.5

Affected versions

0.*

0.1
0.2
0.3
0.3.1
0.4
0.4.1
0.5
0.5.1
0.6
0.6.1
0.6.2
0.7
0.7.1
0.7.2
0.8
0.8.1
0.8.2
0.8.3
0.9
0.9.1
0.9.2
0.9.3
0.9.4
0.9.5
0.9.6
0.10
0.10.1
0.10.2
0.10.3
0.10.4
0.11
0.11.1
0.11.2
0.11.3
0.11.4
0.11.5
0.11.6
0.11.7
0.11.8
0.11.9
0.11.10
0.11.11
0.11.12
0.11.13
0.11.14
0.11.15
0.12
0.12.1
0.12.2
0.13
0.14
0.14.1
0.15.0
0.15.1
0.15.2
0.15.3
0.15.4
0.15.5
0.15.6
0.16.0
0.16.1

1.*

1.0.0rc1
1.0.0
1.0.1

2.*

2.0.0rc1
2.0.0rc2
2.0.0rc3
2.0.0rc4
2.0.0rc5
2.0.0
2.0.1
2.0.2
2.0.3
2.1.0
2.1.1
2.1.2
2.2.0a1
2.2.0
2.2.1
2.2.2
2.2.3
2.3.0
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.3.6
2.3.7
2.3.8

3.*

3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.5
3.0.6
3.1.0
3.1.1
3.1.2
3.1.3
3.1.4

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/01/GHSA-87hc-h4r5-73f7/GHSA-87hc-h4r5-73f7.json"