CVE-2026-12259

See a problem?
Please try reporting it to the source first.

Source

https://cve.org/CVERecord?id=CVE-2026-12259

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-12259.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-12259

Aliases

Downstream

Published

2026-08-03T07:09:35Z

Modified

2026-10-17T02:48:28Z

Severity

5.3 (Medium) CVSS_V3 - CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N CVSS Calculator

Summary

Improper Input Validation in nltk/nltk

Details

In nltk version 3.9.4, the nltk.downloader.Downloader._download_package() function writes downloaded package bytes to disk and may extract them before enforcing SHA-256 or MD5 checksum validation. This allows an attacker to tamper with the package response body for info.url through a compromised mirror, malicious proxy, or other source-substitution condition, leading to the installation of attacker-controlled package bytes. The vulnerability can result in malicious corpus or model content being trusted by downstream users or applications.

Database specific

{
    "cna_assigner":  "@huntr_ai",
    "cwe_ids":  [
        "CWE-494"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12259.json"
}

References

Affected packages

Git / github.com/nltk/nltk

Affected ranges

Type

GIT

Repo

https://github.com/nltk/nltk

Events

Introduced

ad9c96ba00a16923ffe917eacf63f1707bfa2d08

Last Affected

ad9c96ba00a16923ffe917eacf63f1707bfa2d08

Database specific

Show details

{
    "cpe":  "cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:*",
    "extracted_events":  [
        {
            "introduced":  "3.9.4"
        },
        {
            "last_affected":  "3.9.4"
        }
    ],
    "source":  "CPE_STRING"
}

Affected versions

3.*

3.9.4

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-12259.json"