{"cve":"CVE-2026-21860","nvd":{"published":"2026-01-08T19:15:59.000","modified":"2026-06-17T10:19:02.740","status":"Analyzed","description":"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.","cvss_v4":{"vector":"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","score":6.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-67"],"references":["https://github.com/pallets/werkzeug/commit/7ae1d254e04a0c33e241ac1cca4783ce6c875ca3","https://github.com/pallets/werkzeug/security/advisories/GHSA-87hc-h4r5-73f7"],"products":["palletsprojects:werkzeug"],"source":"nvd","synced_at":"2026-10-19T22:19:41.481987139+00:00"},"epss":{"cve":"CVE-2026-21860","score":0.00475,"percentile":0.4106,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-87hc-h4r5-73f7","url":"https://osv.dev/vulnerability/GHSA-87hc-h4r5-73f7","summary":" Werkzeug safe_join() allows Windows special device names with compound extensions","modified":"2026-09-10T03:50:32.862525778Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<3.1.5"],"fixed":["3.1.5"]}]},{"id":"PYSEC-2026-2044","url":"https://osv.dev/vulnerability/PYSEC-2026-2044","summary":" Werkzeug safe_join() allows Windows special device names with compound extensions","modified":"2026-07-07T17:47:56.418445755Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<3.1.5"],"fixed":["3.1.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}