{"id":"CVE-2025-66221","aliases":["ALPINE-CVE-2025-66221","BELL-CVE-2025-66221","CLSA-2026-1772583182","CLSA-2026-1789365574","CLSA-2026-1791365297","EUVD-2025-199893","GHSA-hgf8-39gv-g3f2","PYSEC-2026-2046","ROOT-APP-PYPI-CVE-2025-66221","UBUNTU-CVE-2025-66221","openSUSE-SU-2025:15848-1"],"status":"published","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. 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 patched in version 3.1.4.","severity":{"version":"4.0","score":6.3,"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00547,"percentile":0.46199,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-67"],"published":"2025-11-29T02:28:34Z","modified":"2026-10-28T02:31:13Z","fixes":[{"ecosystem":"PyPI","package":"werkzeug","fixed_in":["3.1.4"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.24","package":"py3-werkzeug","fixed_in":["3.1.4-r0"],"sources":["osv"]},{"ecosystem":"TuxCare:PyPI","package":"werkzeug","fixed_in":["2.3.8.post1+tuxcare","1.0.1.post5+tuxcare"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"rootio-Werkzeug","fixed_in":["2.3.7+root.io.5","3.1.3+root.io.3","3.1.3+root.io.4","2.3.7+root.io.6","3.1.0+root.io.1"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"Werkzeug","fixed_in":["3.1.3+aikido.4","2.3.7+aikido.6"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"python-openapi-core","fixed_in":["0.22.0-1.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.4"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"py3-werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.4-r0"}]}]},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.3.8"},{"fixed":"2.3.8.post1+tuxcare"}]}],"versions":["2.3.8"]},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.1"},{"fixed":"1.0.1.post5+tuxcare"}]}],"versions":["1.0.1","1.0.1.post1+tuxcare","1.0.1.post2+tuxcare","1.0.1.post3+tuxcare","1.0.1.post4+tuxcare"]},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.2.3"},{"fixed":"2.2.3.post6+tuxcare"}]}],"versions":["2.2.3","2.2.3.post1+tuxcare","2.2.3.post3+tuxcare","2.2.3.post4+tuxcare","2.2.3.post5+tuxcare"],"bundled":2},{"source":"osv","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.4"}]}],"versions":["0.1","0.10","0.10.1","0.10.2","0.10.3","0.10.4","0.11","0.11.1","0.11.10","0.11.11","0.11.12","0.11.13","0.11.14","0.11.15","0.11.2","0.11.3","0.11.4","0.11.5","0.11.6","0.11.7","0.11.8","0.11.9","0.12","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","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","1.0.0","1.0.0rc1","1.0.1","2.0.0","2.0.0rc1","2.0.0rc2","2.0.0rc3","2.0.0rc4","2.0.0rc5","2.0.1","2.0.2","2.0.3","2.1.0","2.1.1","2.1.2","2.2.0","2.2.0a1","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","3.0.0","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"]},{"source":"osv","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.4"}]}],"versions":["0.1","0.10","0.10.1","0.10.2","0.10.3","0.10.4","0.11","0.11.1","0.11.10","0.11.11","0.11.12","0.11.13","0.11.14","0.11.15","0.11.2","0.11.3","0.11.4","0.11.5","0.11.6","0.11.7","0.11.8","0.11.9","0.12","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","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","1.0.0","1.0.0rc1","1.0.1","2.0.0","2.0.0rc1","2.0.0rc2","2.0.0rc3","2.0.0rc4","2.0.0rc5","2.0.1","2.0.2","2.0.3","2.1.0","2.1.1","2.1.2","2.2.0","2.2.0a1","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","3.0.0","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"]},{"source":"osv","ecosystem":"Root:PyPI","package":"rootio-Werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.7+root.io.5"},{"fixed":"3.1.3+root.io.3"},{"fixed":"3.1.3+root.io.4"},{"fixed":"2.3.7+root.io.6"},{"fixed":"3.1.0+root.io.1"}]}]},{"source":"osv","ecosystem":"Root:PyPI","package":"Werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.3+aikido.4"},{"fixed":"2.3.7+aikido.6"}]}]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"python-openapi-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0-1.1"}]}]}],"products":[{"vendor":"pallets","product":"werkzeug"},{"vendor":"palletsprojects","product":"werkzeug"}],"references":[{"url":"https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3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Advisory","advisory","web","report"]},{"url":"https://github.com/pallets/werkzeug/commit/4b833376a45c323a189cd11d2362bcffdb1c0c13","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://github.com/pallets/werkzeug/releases/tag/3.1.4","tags":["x_refsource_MISC","Release Notes","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66221","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-hgf8-39gv-g3f2","tags":["advisory"]},{"url":"https://security.alpinelinux.org/vuln/CVE-2025-66221","tags":["advisory"]},{"url":"https://docs.bell-sw.com/security/cves/CVE-2025-66221","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66221.json","tags":["advisory"]},{"url":"https://github.com/pallets/werkzeug","tags":["package"]},{"url":"https://pypi.org/project/werkzeug","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2025-66221","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-66221","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2025-66221","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2025-66221","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. 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 patched in version 3.1.4.","status":"published","published":"2025-11-29T02:28:34.524Z","modified":"2025-12-01T15:35:25.271Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium","assessor":"cna"}],"cwes":["CWE-67"],"updated_at":"2026-11-02T14:32:52.839698Z"}],"euvd":[{"id":"EUVD-2025-199893","description":"Werkzeug is a comprehensive WSGI web application library. 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This issue has been patched in version 3.1.4.","status":"published","published":"2025-11-29T02:28:34Z","modified":"2025-12-01T15:35:25Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium"}],"updated_at":"2026-11-02T19:49:11.947161Z"}],"ghsa":[{"id":"GHSA-hgf8-39gv-g3f2","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug's `safe_join` function allows path segments with Windows device names. On Windows, there are special device names such as `CON`, `AUX`, etc that are implicitly present and readable in every directory. `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.","status":"published","published":"2025-12-02T00:27:38Z","modified":"2025-12-02T00:27:38Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium"}],"cwes":["CWE-67"],"updated_at":"2026-11-02T14:39:11.110487Z"}],"nvd":[{"id":"CVE-2025-66221","description":"Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. 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 patched in version 3.1.4.","status":"published","published":"2025-11-29T03:16:00.05Z","modified":"2026-10-07T20:10:01.97Z","cvss":[{"version":"4.0","score":6.3,"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/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","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"primary"}],"cwes":["CWE-67"],"updated_at":"2026-11-02T14:11:46.94029Z"}],"osv":[{"id":"ALPINE-CVE-2025-66221","description":"Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. 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 patched in version 3.1.4.","status":"published","published":"2025-11-29T03:16:00.05Z","modified":"2026-08-27T22:18:03.011293324Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T15:27:50.269992Z"},{"id":"BELL-CVE-2025-66221","title":"CVE-2025-66221 does not affect BellSoft software","status":"withdrawn","published":"2025-12-03T06:07:47.658143Z","modified":"2026-01-26T09:49:54.719274Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T15:28:22.495824Z"},{"id":"CVE-2025-66221","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. 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