Path Traversal in Nltk
CVE-2026-63312
NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (49.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/nltk/nltk/security/advisories/GHSA-x5ph-mj9p-rfr8 (Exploit, vendor-advisory, Vendor Advisory)
- www.vulncheck.com/advisories/nltk-streambackedcorpusview-bypasses-pathsec-enfor… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-63312?
- CVE-2026-63312 is a high-severity vulnerability in Nltk, classified under Path Traversal. CVSS score: 7.5/10. Published 2026-08-22.
- How severe is CVE-2026-63312?
- High severity. CVSS v3 base score is 7.5 out of 10.