NLTK 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.
PUBLISHED5.2CWE-20
Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading
Problem type
Affected products
nltk
nltk/nltk
<= latest - AFFECTED
References
GitHub Security Advisories
GHSA-v2w2-xcg6-53wj
NLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation...
https://github.com/advisories/GHSA-v2w2-xcg6-53wjNLTK 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.
JSON source
https://cveawg.mitre.org/api/cve/CVE-2026-0848Click to expand
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"dataVersion": "5.2",
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"cveId": "CVE-2026-0848",
"assignerOrgId": "c09c270a-b464-47c1-9133-acb35b22c19a",
"assignerShortName": "@huntr_ai",
"dateUpdated": "2026-03-05T20:48:05.364Z",
"dateReserved": "2026-01-10T23:59:44.115Z",
"datePublished": "2026-03-05T20:48:05.364Z",
"state": "PUBLISHED"
},
"containers": {
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"dateUpdated": "2026-03-05T20:48:05.364Z"
},
"title": "Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading",
"descriptions": [
{
"lang": "en",
"value": "NLTK 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."
}
],
"affected": [
{
"vendor": "nltk",
"product": "nltk/nltk",
"versions": [
{
"version": "unspecified",
"status": "affected",
"versionType": "custom",
"lessThanOrEqual": "latest"
}
]
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],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"description": "CWE-20 Improper Input Validation",
"cweId": "CWE-20",
"type": "CWE"
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]
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],
"references": [
{
"url": "https://huntr.com/bounties/08b109bb-ac24-403f-9422-1c246ce60202"
}
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"metrics": [
{
"cvssV3_0": {
"version": "3.0",
"vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "CHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH",
"baseScore": 10,
"baseSeverity": "CRITICAL"
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}