CVE-2026-12252
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk5th percentile — higher than 5% of all known CVEs
Summary
In 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, but the fix was not applied to these additional classes.
Risk Assessment
An attacker can supply a malicious JAR file, leading to arbitrary code execution in the context of the application using nltk, potentially enabling system compromise, data theft, or further attacks.
Recommendation
Immediately update nltk to version 3.9.4 or later, which includes the fix for these classes. If an update is not possible, avoid using these classes with untrusted JAR paths.
Original NVD description (English source)
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.