Improper Input Validation in nltk/nltk

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-12259
StatePUBLISHED
Assigner@huntr_ai
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-03 08:17:17 UTC
Updated2026-08-03 16:16:26 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.0 5.3 MEDIUM from [email protected]

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS: 0.001000000 probability, percentile 0.010280000 (date 2026-08-04)

Problem Types: CWE-494 | CWE-494 CWE-494 Download of Code Without Integrity Check

VersionSourceTypeScoreSeverityVector
3.0[email protected]Secondary5.3MEDIUMCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
3.0CNADECLARED5.3MEDIUMCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nltk Nltk/nltk affected unspecified latest custom Not specified

References

ReferenceSourceLinkTags
huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d [email protected] huntr.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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