Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading

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Summary

CVECVE-2026-0848
StatePUBLISHED
Assigner@huntr_ai
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-05 21:16:14 UTC
Updated2026-04-21 14:56:46 UTC
DescriptionNLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation in the StanfordSegmenter module. The module dynamically loads external Java .jar files without verification or sandboxing. An attacker can supply or replace the JAR file, enabling the execution of arbitrary Java bytecode at import time. This vulnerability can be exploited through methods such as model poisoning, MITM attacks, or dependency poisoning, leading to remote code execution. The issue arises from the direct execution of the JAR file via subprocess with unvalidated classpath input, allowing malicious classes to execute when loaded by the JVM.

Risk And Classification

Primary CVSS: v3.0 10 CRITICAL from [email protected]

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

EPSS: 0.002900000 probability, percentile 0.524890000 (date 2026-04-22)

Problem Types: CWE-20 | NVD-CWE-noinfo | CWE-20 CWE-20 Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.0[email protected]Secondary10CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.0CNADECLARED10CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.0 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Nltk Nltk All All All All

Vendor Declared Affected Products

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

References

ReferenceSourceLinkTags
huntr.com/bounties/08b109bb-ac24-403f-9422-1c246ce60202 134c704f-9b21-4f2e-91b3-4a467353bcc0 huntr.com Exploit, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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