CVE-2026-0848

CRITICAL

NLTK <=3.9.2 - Remote Code Execution via StanfordSegmenter JAR Loading

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 3 public exploits for CVE-2026-0848. PoCs published by fevar54, HyperPS.

AI-analyzed exploit summary This repository contains a scanner for detecting the presence of vulnerable NLTK installations (CVE-2026-0848) by checking file system paths, pip versions, and local system details. It does not include exploit code but identifies potential targets.

Description

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.

Exploits (3)

nomisec SCANNER
by fevar54 · poc
https://github.com/fevar54/CVE-2026-0848-Scanner---Herramienta-de-Detecci-n

This repository contains a scanner for detecting the presence of vulnerable NLTK installations (CVE-2026-0848) by checking file system paths, pip versions, and local system details. It does not include exploit code but identifies potential targets.

Classification
Scanner 95%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: NLTK (Natural Language Toolkit) <= 3.9.2
No auth needed
Prerequisites: Access to the target system's file system or pip environment
devstral-2 · analyzed Apr 09, 2026 Full analysis →
nomisec WORKING POC
by fevar54 · poc
https://github.com/fevar54/CVE-2026-0848-PoC-Improper-Input-Validation

This repository contains a functional exploit for CVE-2026-0848, demonstrating RCE via a malicious JAR file loaded by NLTK's StanfordSegmenter. The exploit leverages improper input validation to execute arbitrary code when the JAR is loaded.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: NLTK 3.9.2 (StanfordSegmenter)
No auth needed
Prerequisites: Python 3.8+ · Java JDK 8+ · NLTK 3.9.2
devstral-2 · analyzed Apr 09, 2026 Full analysis →
nomisec WRITEUP
by HyperPS · poc
https://github.com/HyperPS/CVE-2026-0848

This repository provides a detailed technical analysis of CVE-2026-0848, a critical vulnerability in NLTK's StanfordSegmenter that allows arbitrary code execution via untrusted JAR loading. It includes a proof-of-concept demonstrating how a malicious JAR can be crafted and executed through NLTK's Java subprocess invocation.

Classification
Writeup 100%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: NLTK <= 3.9.2
No auth needed
Prerequisites: ability to supply or replace a JAR file used by StanfordSegmenter
devstral-2 · analyzed Apr 09, 2026 Full analysis →

References (1)

Core 1
Core References

Scores

CVSS v3 10.0
EPSS 0.0031
EPSS Percentile 54.4%
Attack Vector NETWORK
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact total

Details

CWE
CWE-20
Status published
Products (2)
nltk/nltk < 3.9.2
nltk/nltk/nltk unspecified - latest
Published Mar 05, 2026
Tracked Since Mar 06, 2026