CVE-2026-79657
NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
CRITICAL 9.3EPSS 1.3%
NLTK versions before 3.10.3 contain a remote code execution vulnerability in allowlisted pickle loaders that trust entire module namespaces instead of specific safe callables. Attackers can craft malicious pickle payloads invoking dangerous in-namespace functions like ReppTokenizer._execute and numpy.f2py.crackfortran.myeval through pickle REDUCE to execute arbitrary commands during model or tokenizer artifact loading.
- Affected
- nltk
- CVSS v4.0 VULNCHECK
- 9.3 CRITICAL
CVSS:4.0/AV:N/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
- 9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS v3.1 VULNCHECK
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 1.27% chance of exploitation in the next 30 days, 69th percentile
- Published
- 2026-08-25
- Updated
- 2026-10-08
Proof-of-concept exploits (1)
Security advisories
- nltk/nltk/security/advisories/GHSA-x99w-6fgc-pmfw
- https://www.vulncheck.com/advisories/nltk-before-3.10.3-remote-code-execution-via-unsafe-…