Vulnerability in Nltk
CVE-2026-70626
NLTK versions before 3.9.4 contain a symlink escape vulnerability in CorpusReader.open() that allows local attackers to read arbitrary files outside the corpus root. The vulnerability exists because path validation is lexical and does not account for symlink resolution, enabling attackers to place symlinks inside the corpus root to access files outside the intended boundary.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (8.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 8.9% 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/security/advisories/GHSA-r6gq-whwq-mvg9 (Exploit, vendor-advisory, Vendor Advisory)
- www.vulncheck.com/advisories/nltk-before-symlink-escape-via-corpusreader (Vendor Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-70626?
- CVE-2026-70626 is a medium-severity vulnerability in Nltk, classified under Improper Link Resolution Before File Access. CVSS score: 6.2/10. Published 2026-08-22.
- How severe is CVE-2026-70626?
- Medium severity. CVSS v3 base score is 6.2 out of 10.