CVE-2026-81727

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Source
https://cve.org/CVERecord?id=CVE-2026-81727
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81727.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-81727
Aliases
  • GHSA-f794-5jv7-7672
Downstream
Published
2026-08-27T14:51:19.564Z
Modified
2026-08-30T03:30:44.428292407Z
Severity
  • 6.9 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
NLTK before 3.10.3 Hardlink File Overwrite via downloader
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.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81727.json",
    "cwe_ids": [
        "CWE-59"
    ],
    "cna_assigner": "VulnCheck"
}
References

Affected packages

Git / github.com/nltk/nltk

Affected ranges

Type
GIT
Repo
https://github.com/nltk/nltk
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
303f6e2ba8e4548a5f54fd65d86bb5c9a949f1db
Database specific
Show details 
{
    "source": [
        "AFFECTED_FIELD",
        "DESCRIPTION"
    ],
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "3.10.3"
        }
    ]
}

Affected versions

2.*
2.0.1rc1
2.0.1rc2
2.0.1rc3
2.0.1rc4
3.*
3.0.0b1
3.0.2
3.0.3
3.0.4
3.0.5
3.0a4
3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.3
3.4
3.4.1
3.4.3
3.4.4
3.5
3.5b1
3.6
3.6.1
3.6.2
3.6.5
3.6.6
3.6.7
3.7
3.8
3.8.1
3.8.2
3.9
3.9.1
3.9.2
3.9.3
3.9.4
v.*
v.3.10.1
v3.*
v3.10.0
v3.10.0-rc1
v3.10.0-rc2
v3.10.1
v3.10.1-rc1
v3.10.1-rc2
v3.10.2
v3.10.2-rc1
v3.9.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81727.json"