CVEvulnerability

CVE-2026-12259

6.5 MEDIUM Published 2026-08-03 Modified 2026-10-23 Official page ↗
Status
Analyzed
Published
2026-08-03
Last modified
2026-10-23
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CVSS 3.0 ([email protected])
5.3 MEDIUM — CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Weaknesses
CWE-494

Description

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.

Affected configurations

• nltk nltk 3.9.4

Related

Weakness · CWE (1)

  • CWE-494 Download of Code Without Integrity Check weakness

References