CVE-2026-12252: high-severity vulnerability in nltk/nltk
Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.8epss 0.2%
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.
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected products
nltk · nltk/nltkRelated CVEs — nltk/nltk
In the same product, most dangerous first.
CVE-2021-3828HIGHInefficient Regular Expression Complexity in nltk/nltkEPSS 1.6%CVE-2021-3842HIGHInefficient Regular Expression Complexity in nltk/nltkEPSS 1.6%CVE-2025-14009HIGHZip Slip Vulnerability in nltk/nltk Leading to Remote Code ExecutionEPSS 1.0%CVE-2026-0847HIGHPath Traversal in nltk/nltkEPSS 1.0%CVE-2026-0848CRITICALArbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR LoadingEPSS 0.8%CVE-2026-0846HIGHArbitrary File Read via Absolute Path Input in nltk.util.filestring()EPSS 0.6%