Path Traversal in Nltk Nltk/nltk

CVE-2026-12243

NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The `_UNSAFE_NO_PROTOCOL_RE` regex in `nltk/data.py` checks for literal `../` sequences but fails to account for percent-encoded t…

Vulnerability class: Path Traversal (Directory Traversal)

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-12243?
CVE-2026-12243 is a high-severity vulnerability in Nltk Nltk/nltk, classified under Path Traversal. CVSS score: 7.5/10. Published 2026-06-30.
How severe is CVE-2026-12243?
High severity. CVSS v3 base score is 7.5 out of 10.