Vulnerability · Published Aug 22, 2026 · Assigned by VulnCheck
CVE-2026-71514NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass
Low 2.5
In plain English
A low-severity path traversal in nltk from nltk. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | nltk | no fix listed | DEBIAN-CVE-2026-71514 |
| Debian:13 | nltk | no fix listed | DEBIAN-CVE-2026-71514 |
| Debian:14 | nltk | 3.10.3-1 | DEBIAN-CVE-2026-71514 |
| PyPI | nltk | 3.10.3 | GHSA-cv22-g7mw-8v73 |
| PyPI | nltk | 3.10.3 | PYSEC-2026-3790 |
| Ubuntu:26.10 | nltk | no fix listed | UBUNTU-CVE-2026-71514 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
References
- Patch Commit patch
- https://github.com/nltk/nltk product
- https://github.com/nltk/nltk/blob/v3.10.2/nltk/corpus/reader/crubadan.py#L90-L98 technical-description
- VulnCheck Advisory: NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass third-party-advisory