Path Traversal in Nltk
CVE-2026-109956
NLTK through 3.10.3 contains a path traversal vulnerability in WekaClassifier that allows attackers to bypass nltk.pathsec containment by supplying unvalidated model paths. Attackers controlling the model_filename or model argument can make the weka JVM write files via -d or probe files via -l outside allowed data roots.
Vulnerability class: Path Traversal (Directory Traversal)
Published .
CVSS v3 metric
CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/nltk/nltk/security/advisories/GHSA-j456-xh4h-cpf2 (vendor-advisory)
- www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-wekaclassif… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-109956?
- CVE-2026-109956 is a high-severity vulnerability in Nltk, classified under Path Traversal. CVSS score: 7.0/10. Published 2026-10-13.
- How severe is CVE-2026-109956?
- High severity. CVSS v3 base score is 7.0 out of 10.