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CVE-2026-12252

Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk

7.8 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.19%Unchanged since Jul 4, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.8

Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk

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.

Record
CVE-2026-12252
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
EUVDEUVD-2026-41656 7.8

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.

Record
EUVD-2026-41656
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-9r6g-266r-89x4 7.8

NLTK Stanford wrapper classes execute untrusted JAR files without verification

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.

Record
GHSA-9r6g-266r-89x4
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
NVD 7.8

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.

Record
CVE-2026-12252
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
OSV 7.8

Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk

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.

Record
CVE-2026-12252
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
OSVDEBIAN-CVE-2026-12252 7.8

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.

Record
DEBIAN-CVE-2026-12252
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVGHSA-9r6g-266r-89x4 7.8

NLTK Stanford wrapper classes execute untrusted JAR files without verification

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.

Record
GHSA-9r6g-266r-89x4
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
OSVPYSEC-2026-2085 7.8

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.

Record
PYSEC-2026-2085
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-12252 7.8

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.

Record
UBUNTU-CVE-2026-12252
CVSS 3.0
7.8 HighCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:11587-1 No score

python313-nltk-3.10.3-1.1 on GA media

These are all security issues fixed in the python313-nltk-3.10.3-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11587-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nltk
PyPI
before 3.9.4
3.9.4
nltk
Debian:12
All versions, plus listed versions
3.10.0-13.10.1-13.10.3-13.8-13.8.1-1
Show 4 moreShow less
3.9.1-13.9.1-23.9.2-13.9.3-1
None known
nltk
Debian:13
All versions, plus listed versions
3.10.0-13.10.1-13.10.3-13.9.1-23.9.2-13.9.3-1
None known
nltk
Debian:14
before 3.10.3-1, plus listed versions
3.10.0-13.10.1-13.9.1-23.9.2-13.9.3-1
3.10.3-1
nltk
PyPI
before 3.9.4, plus listed versions
0.80.90.9.30.9.40.9.5
Show 45 moreShow less
0.9.60.9.70.9.80.9.92.0.12.0.1rc12.0.1rc2-git2.0.1rc32.0.1rc42.0.22.0.32.0.42.0.52.0b42.0b52.0b62.0b72.0b82.0b93.0.03.0.0b13.0.0b23.0.13.0.23.0.33.0.43.0.53.13.23.2.13.2.23.2.33.2.43.2.53.33.43.4.13.4.23.4.33.4.43.4.53.53.5b13.63.6.1
3.9.4
nltk
Ubuntu:Pro:14.04:LTS
All versions, plus listed versions
2.0~b9-0ubuntu42.0~b9-0ubuntu4.1~esm22.0~b9-0ubuntu4.1~esm42.0~b9-0ubuntu4.1~esm52.0~b9-0ubuntu4.1~esm6
None known
nltk
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
3.0.4-13.0.5-13.1-13.1-1ubuntu0.13.1-1ubuntu0.1+esm13.1-1ubuntu0.1+esm23.1-1ubuntu0.1+esm33.1-1ubuntu0.1+esm4
None known
nltk
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
3.2.4-13.2.5-13.2.5-1ubuntu0.13.2.5-1ubuntu0.1+esm13.2.5-1ubuntu0.1+esm23.2.5-1ubuntu0.1+esm33.2.5-1ubuntu0.1+esm4
None known
nltk
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
3.4.5-13.4.5-23.4.5-2ubuntu0.1~esm13.4.5-2ubuntu0.1~esm23.4.5-2ubuntu0.1~esm33.4.5-2ubuntu0.1~esm4
None known
nltk
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
3.5-13.6.5-13.6.7-13.7-13.7-1ubuntu0.1~esm13.7-1ubuntu0.1~esm2
None known
Show 5 moreShow less
Affected packages
PackageAffectedFixed
nltk
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
3.8.1-13.8.1-1ubuntu0.1~esm13.8.1-1ubuntu0.1~esm2
None known
nltk
Ubuntu:25.10
All versions, plus listed versions
3.9.1-2
None known
nltk
Ubuntu:26.10
All versions, plus listed versions
3.9.2-13.9.3-13.10.0-13.10.1-13.10.3-1
None known
nltk
Ubuntu:Pro:26.04:LTS
All versions, plus listed versions
3.9.1-23.9.1-2build13.9.2-13.9.2-1ubuntu0.1~esm13.9.2-1ubuntu0.1~esm2
None known
python-nltk
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
before 3.10.3-1.1
3.10.3-1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-12252 is a high vulnerability (CVSS 7.8) in Nltk, published July 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 9th percentile. Fixed in nltk 3.9.4.

References

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Left out here: 14 versions. The JSON record has them.

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