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.
History

Thu, 27 Aug 2026 16:45:00 +0000

Type Values Removed Values Added
Description 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.
Title NLTK before 3.10.3 Hardlink File Overwrite via downloader
First Time appeared Nltk
Nltk nltk
Weaknesses CWE-59
CPEs cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
Vendors & Products Nltk
Nltk nltk
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-27T17:43:34.469Z

Reserved: 2026-08-27T11:15:29.420Z

Link: CVE-2026-81727

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-27T17:21:03.533

Modified: 2026-08-27T17:21:03.533

Link: CVE-2026-81727

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.