Bug 2496984 (CVE-2026-12252)

Summary: CVE-2026-12252 nltk: nltk: Arbitrary Code Execution via Untrusted JAR File Loading
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anpicker, bparees, dschmidt, ebourniv, hasun, jfula, jkoehler, jlanda, jowilson, kshier, lgallett, lphiri, nyancey, ometelka, ptisnovs, sbunciak, simaishi, stcannon, syedriko, teagle, xdharmai, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the `nltk` library. Several Stanford interface classes within `nltk` are susceptible to arbitrary code execution. This vulnerability allows a local attacker to execute malicious code by providing an untrusted Java Archive (JAR) file, as the system lacks integrity verification for these files.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2497246, 2497247    
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Description OSIDB Bzimport 2026-07-04 02:01:17 UTC 
In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes (StanfordPOSTagger, StanfordNERTagger, StanfordParser, StanfordDependencyParser, and StanfordNeuralDependencyParser) are vulnerable to untrusted JAR code execution. These classes accept user-controllable JAR paths and execute them via the `java()` function, which invokes `subprocess.Popen()` without integrity verification. This vulnerability is identical to CVE-2026-0848, which was fixed for StanfordSegmenter by adding SHA256 verification. However, the fix was not applied to these additional classes, leaving them susceptible to arbitrary code execution when loading untrusted JAR files.