{"cve":"CVE-2026-27199","nvd":{"published":"2026-02-21T06:17:00.710","modified":"2026-06-17T10:26:50.207","status":"Analyzed","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.","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/f407712fdc60a09c2b3f4fe7db557703e5d9338d","https://github.com/pallets/werkzeug/releases/tag/3.1.6","https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6x"],"products":["palletsprojects:werkzeug"],"source":"nvd","synced_at":"2026-10-19T22:24:17.937441719+00:00"},"epss":{"cve":"CVE-2026-27199","score":0.00631,"percentile":0.50282,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-29vq-49wr-vm6x","url":"https://osv.dev/vulnerability/GHSA-29vq-49wr-vm6x","summary":" Werkzeug safe_join() allows Windows special device names","modified":"2026-09-10T03:50:33.709103081Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<3.1.6"],"fixed":["3.1.6"]}]},{"id":"PYSEC-2026-2320","url":"https://osv.dev/vulnerability/PYSEC-2026-2320","summary":"","modified":"2026-07-13T07:15:48.093424944Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<3.1.6"],"fixed":["3.1.6"]}]}],"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."]}