{"id":"CVE-2026-21860","aliases":["ALPINE-CVE-2026-21860","CLSA-2026-1789452203","CLSA-2026-1789452814","CLSA-2026-1789453348","EUVD-2026-1425","GHSA-87hc-h4r5-73f7","PYSEC-2026-2044","ROOT-APP-PYPI-CVE-2026-21860","UBUNTU-CVE-2026-21860"],"status":"published","title":"Werkzeug safe_join() allows Windows special device names with compound extensions","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.","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":"2026-11-11","score":0.00475,"percentile":0.41488,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-67"],"published":"2026-01-08T18:34:05Z","modified":"2026-10-28T02:31:14Z","fixes":[{"ecosystem":"PyPI","package":"werkzeug","fixed_in":["3.1.5"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.24","package":"py3-werkzeug","fixed_in":["3.1.5-r0"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"rootio-Werkzeug","fixed_in":["3.1.3+root.io.3","3.1.3+root.io.4","3.1.0+root.io.1"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"Werkzeug","fixed_in":["3.1.3+aikido.4"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"py3-werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5-r0"}]}]},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.1"},{"fixed":"1.0.1.post6+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","1.0.1.post5+tuxcare"],"bundled":2},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.2.3"},{"fixed":"2.2.3.post5+tuxcare"}]}],"versions":["2.2.3","2.2.3.post1+tuxcare","2.2.3.post3+tuxcare","2.2.3.post4+tuxcare"],"bundled":3},{"source":"osv","ecosystem":"TuxCare:PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.3.8"},{"fixed":"2.3.8.post3+tuxcare"}]}],"versions":["2.3.8","2.3.8.post1+tuxcare","2.3.8.post2+tuxcare"],"bundled":4},{"source":"osv","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5"}]}],"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","3.1.4"]},{"source":"osv","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5"}]}],"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","3.1.4"]},{"source":"osv","ecosystem":"Root:PyPI","package":"rootio-Werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.3+root.io.3"},{"fixed":"3.1.3+root.io.4"},{"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"}]}]}],"products":[{"vendor":"pallets","product":"werkzeug"},{"vendor":"palletsprojects","product":"werkzeug"}],"references":[{"url":"https://github.com/pallets/werkzeug/security/advisories/GHSA-87hc-h4r5-73f7","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/pallets/werkzeug/commit/7ae1d254e04a0c33e241ac1cca4783ce6c875ca3","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21860","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-87hc-h4r5-73f7","tags":["advisory"]},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-21860","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21860.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-2026-21860","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-21860","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-21860","title":"Werkzeug safe_join() allows Windows special device names with compound extensions","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.","status":"published","published":"2026-01-08T18:34:05.39Z","modified":"2026-01-08T18:50:34.504Z","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":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-1425","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.","status":"published","published":"2026-01-08T18:34:05Z","modified":"2026-01-08T18:50:34Z","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":"2026-11-02T19:48:54.487856Z"}],"ghsa":[{"id":"GHSA-87hc-h4r5-73f7","title":" Werkzeug safe_join() allows Windows special device names with compound extensions","description":"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 `.\n\nThis 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.\n\n`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":"2026-01-08T19:51:21Z","modified":"2026-02-02T19:57:32Z","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"},{"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"}],"cwes":["CWE-67"],"updated_at":"2026-11-02T14:39:21.558748Z"}],"nvd":[{"id":"CVE-2026-21860","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.","status":"published","published":"2026-01-08T19:15:59Z","modified":"2026-06-17T10:19:02.74Z","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":"2026-11-02T14:12:03.683495Z"}],"osv":[{"id":"ALPINE-CVE-2026-21860","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.","status":"published","published":"2026-01-08T19:15:59Z","modified":"2026-10-01T02:17:49.207247018Z","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":"CVE-2026-21860","title":"Werkzeug safe_join() allows Windows special device names with compound extensions","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.","status":"published","published":"2026-01-08T18:34:05.39Z","modified":"2026-11-11T10:30:53.972336155Z","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":"2026-11-11T11:06:42.044923Z"},{"id":"GHSA-87hc-h4r5-73f7","title":" Werkzeug safe_join() allows Windows special device names with compound extensions","description":"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 `.\n\nThis 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.\n\n`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":"2026-01-08T19:51:21Z","modified":"2026-09-10T03:50:32.862525778Z","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"},{"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":"2026-11-02T15:46:42.077781Z"},{"id":"PYSEC-2026-2044","title":" Werkzeug safe_join() allows Windows special device names with compound extensions","description":"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 `.\n\nThis 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.\n\n`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":"2026-07-07T16:03:17.057343Z","modified":"2026-07-07T17:47:56.418445755Z","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"},{"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":"2026-11-02T15:52:55.537808Z"},{"id":"ROOT-APP-PYPI-CVE-2026-21860","title":"CVE-2026-21860 in rootio-Werkzeug - Patched by Root","description":"Root has patched CVE-2026-21860 in the rootio-Werkzeug package for Root:PyPI. Multiple fixed versions available.","status":"published","published":"2026-06-23T15:42:44Z","modified":"2026-06-23T18:30:14.208577653Z","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":"2026-11-02T15:53:27.940619Z"},{"id":"UBUNTU-CVE-2026-21860","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.","status":"withdrawn","published":"2026-01-09T00:00:00Z","modified":"2026-01-14T21:53:55.758731Z","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":"2026-11-02T16:56:01.334185Z"},{"id":"CLSA-2026-1789452203","title":"TuxCare security update for werkzeug (2 CVEs)","description":"TuxCare rebuilt werkzeug to address 2 CVEs. Fixed in 1.0.1.post6+tuxcare.","status":"published","published":"2026-09-15T06:03:23Z","modified":"2026-10-15T09:48:01.817471843Z","updated_at":"2026-11-02T15:43:47.938828Z"},{"id":"CLSA-2026-1789452814","title":"TuxCare security update for werkzeug (3 CVEs)","description":"TuxCare rebuilt werkzeug to address 3 CVEs. Fixed in 2.2.3.post5+tuxcare.","status":"published","published":"2026-09-15T06:13:34Z","modified":"2026-10-15T09:48:01.741067831Z","updated_at":"2026-11-02T15:43:47.938828Z"},{"id":"CLSA-2026-1789453348","title":"TuxCare security update for werkzeug (4 CVEs)","description":"TuxCare rebuilt werkzeug to address 4 CVEs. Fixed in 2.3.8.post3+tuxcare.","status":"published","published":"2026-09-15T06:22:28Z","modified":"2026-10-15T09:48:01.720371915Z","updated_at":"2026-11-02T15:43:47.938828Z"}]}}