Path Traversal in Nltk
CVE-2026-71514
NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader. _load_lang_ngrams joins the corpus root with crubadan_code, the column-0 value read from the corpus table.txt mapping file, and opens the result with the builtin open() rather than the pathsec-validated opener, so os.path.join discards the root when that value is absolute and the read escapes the corpus directory without the containment check nltk.pathsec applies when ENFORCE is set. An attacker who controls a corpus package can disclose file contents outside the corpus root through lang_freq, limited to paths ending in -3grams.txt whose contents parse as token count lines.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 2.5 (Low). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (5.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 5.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
Weakness classification (CWE)
References
- github.com/nltk/nltk/commit/10d34b3f4fe3fec74b76527a409eb0acbac2e8ab (Patch, patch)
- github.com/nltk/nltk (Product, product)
- github.com/nltk/nltk/blob/v3.10.2/nltk/corpus/reader/crubadan.py (technical-description, Patch)
- www.vulncheck.com/advisories/nltk-through-path-traversal-via-crubadancorpusread… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-71514?
- CVE-2026-71514 is a low-severity vulnerability in Nltk, classified under Path Traversal. CVSS score: 2.5/10. Published 2026-08-22.
- How severe is CVE-2026-71514?
- Low severity. CVSS v3 base score is 2.5 out of 10.