CVE-2025-71408: NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.coll

Q: How do I fix CVE-2025-71408?

nltk: upgrade to 3.9.3. Exact commands for each OS are on this page.

Q: Is CVE-2025-71408 being exploited?

CVE-2025-71408 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-71408 affect?

CVE-2025-71408 affects nltk. Severity is high (CVSS 7.8). 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

Q: How urgent is CVE-2025-71408?

Priority 37/100. High severity; Public exploit reference

Routine

HIGH 7.8UPGRADE

CVE-2025-71408 is a high-severity flaw (CVSS 7.8) affecting nltk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-95
Published	2026-07-24
Last modified	2026-10-08

Publisher (CNA): VulnCheck · Vendor: nltk

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-24 22:16 UTCPublished CVE record published
2026-10-08 16:16 UTCUpdated Record last modified

nltk nltk UPGRADE

Affected: < 3.9.3

Fixed in: 3.9.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nltk || rpm -q nltk || nltk --version

2. UPGRADE to 3.9.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nltk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nltk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-71408?

nltk: upgrade to 3.9.3. Exact commands for each OS are on this page.

Is CVE-2025-71408 being exploited?

CVE-2025-71408 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-71408 affect?

CVE-2025-71408 affects nltk. Severity is high (CVSS 7.8). 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

How urgent is CVE-2025-71408?

Priority 37/100. High severity; Public exploit reference

Software pages

Python vulnerabilities

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References

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