{"id":"UBUNTU-CVE-2025-71408","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.","modified":"2026-07-29T07:53:10Z","published":"2026-07-24T22:16:00Z","upstream":["CVE-2025-71408"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2025-71408"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2025-71408"},{"type":"REPORT","url":"https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/"},{"type":"REPORT","url":"https://github.com/nltk/nltk/pull/3465"},{"type":"REPORT","url":"https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac"},{"type":"REPORT","url":"https://github.com/nltk/nltk/releases/tag/3.9.3"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments"}],"affected":[{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0~b9-0ubuntu4","2.0~b9-0ubuntu4.1~esm2","2.0~b9-0ubuntu4.1~esm4","2.0~b9-0ubuntu4.1~esm5","2.0~b9-0ubuntu4.1~esm6"],"ecosystem_specific":{"binaries":[{"binary_version":"2.0~b9-0ubuntu4.1~esm6","binary_name":"python-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.4-1","3.0.5-1","3.1-1","3.1-1ubuntu0.1","3.1-1ubuntu0.1+esm1","3.1-1ubuntu0.1+esm2","3.1-1ubuntu0.1+esm3","3.1-1ubuntu0.1+esm4"],"ecosystem_specific":{"binaries":[{"binary_version":"3.1-1ubuntu0.1+esm4","binary_name":"python-nltk"},{"binary_version":"3.1-1ubuntu0.1+esm4","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.4-1","3.2.5-1","3.2.5-1ubuntu0.1","3.2.5-1ubuntu0.1+esm1","3.2.5-1ubuntu0.1+esm2","3.2.5-1ubuntu0.1+esm3","3.2.5-1ubuntu0.1+esm4"],"ecosystem_specific":{"binaries":[{"binary_version":"3.2.5-1ubuntu0.1+esm4","binary_name":"python-nltk"},{"binary_version":"3.2.5-1ubuntu0.1+esm4","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.5-1","3.4.5-2","3.4.5-2ubuntu0.1~esm1","3.4.5-2ubuntu0.1~esm2","3.4.5-2ubuntu0.1~esm3","3.4.5-2ubuntu0.1~esm4"],"ecosystem_specific":{"binaries":[{"binary_version":"3.4.5-2ubuntu0.1~esm4","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.5-1","3.6.5-1","3.6.7-1","3.7-1","3.7-1ubuntu0.1~esm1","3.7-1ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"3.7-1ubuntu0.1~esm2","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.8.1-1","3.8.1-1ubuntu0.1~esm1","3.8.1-1ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"3.8.1-1ubuntu0.1~esm2","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.9.1-2","3.9.1-2build1","3.9.2-1","3.9.2-1ubuntu0.1~esm1","3.9.2-1ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"3.9.2-1ubuntu0.1~esm2","binary_name":"python3-nltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-71408.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}