CVE-2025-71408
NLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.5
NLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments
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.
- Record
CVE-2025-71408- CVSS 4.0
- 8.5 High
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 - CVSS 3.1
- 7.8 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-95
- Updated
- 2026-11-02
EUVDEUVD-2025-210509
8.5
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.
- Record
EUVD-2025-210509- CVSS 4.0
- 8.5 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-848c-c2cx-j7qx
8.5
NLTK vulnerable to Eval Injection via collocations CLI arguments
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.
- Record
GHSA-848c-c2cx-j7qx- CVSS 4.0
- 8.5 High
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 - CVSS 3.1
- 7.8 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-95
- Updated
- 2026-11-02
NVD
8.5
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.
- Record
CVE-2025-71408- CVSS 4.0
- 8.5 High
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 3.1
- 7.8 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-95
- Updated
- 2026-11-02
OSV
8.5
NLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments
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.
- Record
CVE-2025-71408- CVSS 4.0
- 8.5 High
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 - Weakness
- CWE-95
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2025-71408
8.5
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.
- Record
DEBIAN-CVE-2025-71408- CVSS 4.0
- 8.5 High
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 - Updated
- 2026-11-02
OSVGHSA-848c-c2cx-j7qx
8.5
NLTK vulnerable to Eval Injection via collocations CLI arguments
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.
- Record
GHSA-848c-c2cx-j7qx- CVSS 4.0
- 8.5 High
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 - CVSS 3.1
- 7.8 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-95
- Updated
- 2026-11-02
OSVPYSEC-2026-3657
8.5
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.
- Record
PYSEC-2026-3657- CVSS 4.0
- 8.5 High
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 - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-71408
8.5
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.
- Record
UBUNTU-CVE-2025-71408- CVSS 4.0
- 8.5 High
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 - CVSS 3.1
- 7.8 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
nltkPyPI |
before 3.9.3 | 3.9.3 |
nltkDebian:12 |
All versions, plus listed versions 3.10.0-13.10.1-13.10.3-13.8-13.8.1-1 Show 4 moreShow less3.9.1-13.9.1-23.9.2-13.9.3-1 |
None known |
nltkDebian: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 |
nltkDebian:14 |
before 3.9.3-1, plus listed versions 3.9.1-23.9.2-1 |
3.9.3-1 |
nltkPyPI |
before 3.9.3, plus listed versions 0.80.90.9.30.9.40.9.5 Show 45 moreShow less0.9.60.9.70.9.80.9.92.0.12.0.1rc12.0.1rc2-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 |
3.9.3 |
nltkUbuntu: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 |
nltkUbuntu: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 |
nltkUbuntu: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 |
nltkUbuntu: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 |
nltkUbuntu: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 |
nltkUbuntu: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 |
nltkUbuntu: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 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-71408 is a high vulnerability (CVSS 8.5) in Nltk, published July 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 18th percentile. Fixed in nltk 3.9.3.
References
aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval
github.com/nltk/nltk/releases/tag/3.9.3
github.com/nltk/nltk/pull/3465
github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac
vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments
nvd.nist.gov/vuln/detail/CVE-2025-71408
Show 7 moreShow less
github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3657.yaml
github.com/advisories/GHSA-848c-c2cx-j7qx
github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71408.json
github.com/nltk/nltk
security-tracker.debian.org/tracker/CVE-2025-71408
ubuntu.com/security/CVE-2025-71408
cve.org/CVERecord?id=CVE-2025-71408
Left out here: 13 versions. The JSON record has them.