{"id":"CVE-2026-27199","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-27199","generatedAt":"2026-10-28T09:27:02.234Z","title":"Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments.","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.","published":"2026-02-21T06:17:01.000Z","lastModified":"2026-06-17T10:26:50.000Z","status":"Analyzed","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":6.3,"severity":"MEDIUM","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/M"},"cwe":["CWE-67"],"affected":["palletsprojects/werkzeug"],"epss":{"score":0.00631,"percentile":0.5006,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.63%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d","tags":["Patch"],"source":"security-advisories@github.com"},{"url":"https://github.com/pallets/werkzeug/releases/tag/3.1.6","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6x","tags":["Vendor Advisory"],"source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-27199","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}