CVE-2026-12259
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
63/100
Published: 2026-08-03
Modified: 2026-10-23
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
Integ. Impact
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
Required
S:
Unchanged
C:
None
I:
High
A:
None
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.
Weakness Classification (1)
References & Advisories (1)
Permissions Required