{"id":"CVE-2025-71408","aliases":["GHSA-848c-c2cx-j7qx","PYSEC-2026-3657"],"url":"https://o3.security/vulnerability/CVE-2025-71408","summary":"NLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments","details":"NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the __main__ block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.","published":"2026-07-24T21:07:49.610Z","modified":"2026-08-12T19:59:11.940439452Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"nltk","fixedVersion":"3.9.3"}],"fix":{"url":"https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac","label":"nltk/nltk@66f1409"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71408.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-71408"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments"},{"type":"FIX","url":"https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac"},{"type":"FIX","url":"https://github.com/nltk/nltk/pull/3465"},{"type":"FIX","url":"https://github.com/nltk/nltk/releases/tag/3.9.3"},{"type":"PACKAGE","url":"https://github.com/nltk/nltk"},{"type":"EVIDENCE","url":"https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T19:59:11.940439452Z"}}