{"id":"CVE-2026-81727","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-81727","summary":"NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite…","details":"NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader directory can create hardlinks pointing to outside-root files that are then overwritten during normal package extraction, mutating files outside the intended install tree.","published":"2026-08-27T17:21:03.533","modified":"2026-08-27T17:21:03.533","cvss":{"score":7.1,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672"},{"type":"WEB","url":"https://www.vulncheck.com/advisories/nltk-before-3.10.3-hardlink-file-overwrite-via-downloader"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T17:21:03.533"}}