CVE-2026-0848
Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading
- Published
- Mar 5, 2026
- Updated
- Mar 6, 2026
- Assigning CNA
- @huntr_ai
- Evidence observed
- Aug 25, 2026
Primary CVSS
nvd · CVSS 3.0
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HLow · next 30 days
- Percentile
- 54.7%
- Model date
- Oct 15, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
nltk.tokenize.StanfordSegmenter dynamically loads external Java .jar files without verification or sandboxing. If an attacker can supply or replace the JAR (e.g., a poisoned model download, MITM package swap, or dependency poisoning), arbitrary Java bytecode executes at import time.
PoC de CVE-2026-0848: validacion de entrada indebida en NLTK que permite ejecucion de codigo via StanfordSegmenter.
Responsible use
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