Bug 2444957 (CVE-2026-0848)

Summary: CVE-2026-0848 nltk: NLTK: Arbitrary code execution via unvalidated Java Archive (JAR) file loading
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: anpicker, bparees, ebourniv, hasun, jfula, jkoehler, jowilson, jwong, lgallett, lphiri, nyancey, omaciel, ometelka, ptisnovs, sbunciak, syedriko, teagle, ttakamiy, xdharmai
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A code injection flaw was found in nltk. The StanfordSegmenter module in NLTK (Natural Language Toolkit) is vulnerable to arbitrary code execution due to improper input validation. An attacker can exploit this by supplying or replacing Java Archive (JAR) files, which are dynamically loaded without verification or sandboxing. This allows for the execution of arbitrary Java bytecode at import time, potentially leading to remote code execution through methods such as model poisoning, Man-in-the-Middle (MITM) attacks, or dependency poisoning.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-03-05 21:01:42 UTC 
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.