PYSEC-2026-3657

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/nltk/PYSEC-2026-3657.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-3657
Aliases
Published
2026-07-24T22:16:50.063Z
Modified
2026-08-11T10:00:03.261022208Z
Severity
  • 8.5 (High) CVSS_V4 - CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X CVSS Calculator
Summary
[none]
Details

NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the main block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.

References

Affected packages

PyPI / nltk

Package

Name
nltk
View open source insights on deps.dev
Purl
pkg:pypi/nltk

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3.9.3

Affected versions

2.*
2.0.1rc2-git
2.0b4
2.0b5
2.0b6
2.0b7
2.0b8
2.0b9
2.0.1rc1
2.0.1rc3
2.0.1rc4
2.0.1
2.0.2
2.0.3
2.0.4
2.0.5
0.*
0.8
0.9
0.9.3
0.9.4
0.9.5
0.9.6
0.9.7
0.9.8
0.9.9
3.*
3.0.0b1
3.0.0b2
3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.5
3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.3
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.5b1
3.5
3.6
3.6.1
3.6.2
3.6.3
3.6.4
3.6.5
3.6.6
3.6.7
3.7
3.8
3.8.1
3.9b1
3.9
3.9.1
3.9.2

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/nltk/PYSEC-2026-3657.yaml"