{"id":"CVE-2026-27199","aliases":["ALPINE-CVE-2026-27199","BELL-CVE-2026-27199","CLSA-2026-1789452203","CLSA-2026-1789452814","CLSA-2026-1789453348","EUVD-2026-7732","GHSA-29vq-49wr-vm6x","PYSEC-2026-2320","ROOT-APP-PYPI-CVE-2026-27199"],"status":"published","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","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":0.00631,"percentile":0.50611,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-67"],"published":"2026-02-19T20:32:45Z","modified":"2026-10-28T02:30:25Z","exploits":[{"source":"pocgithub","id":"alimezar/CVE-2026-27199-werkzeug-safe-join-bypass-PoC","title":"alimezar/CVE-2026-27199-werkzeug-safe-join-bypass-PoC","date":"2026-02-20","url":"https://github.com/alimezar/CVE-2026-27199-werkzeug-safe-join-bypass-PoC"}],"fixes":[{"ecosystem":"PyPI","package":"werkzeug","fixed_in":["3.1.6"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.24","package":"py3-werkzeug","fixed_in":["3.1.6-r0"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"rootio-werkzeug","fixed_in":["3.1.5+root.io.1"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"rootio-Werkzeug","fixed_in":["3.1.1+root.io.1","3.1.3+root.io.1","3.1.1+root.io.2","3.1.3+root.io.2","3.1.3+root.io.3","3.1.1+root.io.3","3.1.3+root.io.4","3.1.0+root.io.1"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"Werkzeug","fixed_in":["3.1.1+aikido.3","3.1.3+aikido.4"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.6"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"py3-werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.6-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":"3.1.6"}]}],"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","3.1.5"]},{"source":"osv","ecosystem":"PyPI","package":"werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.6"}]}],"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","3.1.5"]},{"source":"osv","ecosystem":"Root:PyPI","package":"rootio-werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5+root.io.1"}]}]},{"source":"osv","ecosystem":"Root:PyPI","package":"rootio-Werkzeug","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.1+root.io.1"},{"fixed":"3.1.3+root.io.1"},{"fixed":"3.1.1+root.io.2"},{"fixed":"3.1.3+root.io.2"},{"fixed":"3.1.3+root.io.3"},{"fixed":"3.1.1+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":"3.1.1+aikido.3"},{"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-29vq-49wr-vm6x","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web"]},{"url":"https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/pallets/werkzeug/releases/tag/3.1.6","tags":["x_refsource_MISC","Release Notes","web","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27199","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-29vq-49wr-vm6x"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-27199","tags":["advisory"]},{"url":"https://docs.bell-sw.com/security/cves/CVE-2026-27199","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27199.json","tags":["advisory"]},{"url":"https://github.com/pallets/werkzeug","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-27199","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T05:15:53.335Z","modified":"2026-02-24T19:02:19.689Z","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":"2026-11-02T14:19:48.826324Z"}],"euvd":[{"id":"EUVD-2026-7732","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T05:15:53Z","modified":"2026-02-24T19:02:19Z","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":"2026-11-02T19:48:29.551855Z"}],"ghsa":[{"id":"GHSA-29vq-49wr-vm6x","title":" Werkzeug safe_join() allows Windows special device names","description":"Werkzeug's `safe_join` function allows Windows device names as filenames if when preceded by other path segments.\n\nThis was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that `safe_join` accepts paths with multiple segments, such as `example/NUL`.\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":"2026-02-19T20:32:45Z","modified":"2026-02-23T22:27:39Z","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":"2026-11-02T14:39:26.881079Z"}],"nvd":[{"id":"CVE-2026-27199","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T06:17:00.71Z","modified":"2026-06-17T10:26:50.207Z","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":"2026-11-02T14:12:06.63895Z"}],"osv":[{"id":"ALPINE-CVE-2026-27199","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T06:17:00.71Z","modified":"2026-10-01T02:17:49.220891264Z","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-2026-27199","title":"CVE-2026-27199 does not affect BellSoft software","status":"withdrawn","published":"2026-03-04T09:54:53.863879Z","modified":"2026-03-13T18:10:37.128401Z","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":"2026-11-02T15:28:23.315185Z"},{"id":"CVE-2026-27199","title":"Werkzeug safe_join() allows Windows special device names","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T05:15:53.335Z","modified":"2026-10-28T02:30:25.125932149Z","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":"2026-11-02T15:45:00.180685Z"},{"id":"GHSA-29vq-49wr-vm6x","title":" Werkzeug safe_join() allows Windows special device names","description":"Werkzeug's `safe_join` function allows Windows device names as filenames if when preceded by other path segments.\n\nThis was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that `safe_join` accepts paths with multiple segments, such as `example/NUL`.\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":"2026-02-19T20:32:45Z","modified":"2026-09-10T03:50:33.709103081Z","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":"2026-11-02T15:46:34.338541Z"},{"id":"PYSEC-2026-2320","description":"Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function 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 fixed in version 3.1.6.","status":"published","published":"2026-02-21T06:17:00.71Z","modified":"2026-07-13T07:15:48.093424944Z","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":"2026-11-02T15:52:55.537808Z"},{"id":"ROOT-APP-PYPI-CVE-2026-27199","title":"CVE-2026-27199 in rootio-werkzeug - Patched by Root","description":"Root has patched CVE-2026-27199 in the rootio-werkzeug package for Root:PyPI. Multiple fixed versions available.","status":"published","published":"2026-06-23T15:42:44Z","modified":"2026-06-23T18:30:15.909754696Z","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":"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"}]}}