CVE-2026-70626
NLTK before 3.9.4 Symlink Escape via CorpusReader
HIGH 8.6EPSS 0.2%
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.
- Affected
- nltk
- CVSS v4.0 VULNCHECK
- 8.6 HIGH
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v4.0 GitHub
- 8.6 HIGH
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS v3.1 VULNCHECK
- 6.2 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - EPSS
- 0.20% chance of exploitation in the next 30 days, 9th percentile
- Published
- 2026-08-22
- Updated
- 2026-08-24
Proof-of-concept exploits (1)
Security advisories
- nltk/nltk/security/advisories/GHSA-r6gq-whwq-mvg9
- https://www.vulncheck.com/advisories/nltk-before-symlink-escape-via-corpusreader