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VulnerabilityPublished Updated

CVE-2026-109956: nltk · Path Traversal

Affects nltkSource CVE Database V5

0

Public exploit available · CVSS 8.3 High.

Data as of 26 Oct 2026, 20:12 UTC

CVSS 4.0 base score
8.3High
How severe the flaw is on the 0–10 CVSS scale.
CISA SSVC
Exploitation
Proof of concept is public or traded
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-26.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 13 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: evidence found.

    CISA SSVC: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by VulnCheck

    , 2 hours before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. CISA SSVC assessment

    proof of concept public

    , 13 days after disclosure

  4. In Threat Radar

    record ingested

    , 13 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
nltknltkAffected
  • <=3.10.3
Fixed in–
PyPInltkpkg:pypi/nltkOther threatsAffected
  • <=3.10.3
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Since the vulnerability is in versions up to 3.10.3, users should upgrade to a version later than 3.10.3 if available. If no fixed version exists yet, users should avoid passing untrusted input to the model_filename or model arguments in WekaClassifier to prevent exploitation. Monitor the vendor advisory for updates and apply official patches once released.

Description

NLTK versions up to 3.10.3 have a path traversal vulnerability in the WekaClassifier component. This flaw allows attackers who control the model filename or model argument to bypass path containment checks and cause the Weka JVM to write or probe files outside of permitted directories.

References

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