High severity · published Jul 4, 2026
CVE-2026-12252
Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk
7.8
CVSS
0.2%
EPSS
No
On KEV
Description
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 vector
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NL
nltk/nltk · nltk
through latest · source: vendor
NL
Nltk · Nltk
through 3.9.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12252
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-12252
Exploit
https://huntr.com/bounties/f5c93982-0cc9-4e2e-bb85-1b6ab29a2efb
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