CVE-2026-71514: nltk Path Traversal

Vulnerability summary

CVE-2026-71514 is a low (CVSS 3.3) Path Traversal vulnerability in nltk. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6.1% of scored vulnerabilities.

Timeline

1. 22-08-2026
   PublishedVulnerability first disclosed.
2. 24-08-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.