{"id":"CVE-2026-63310","summary":"NLTK before 3.9.3 Missing Post-Download Integrity Verification","details":"NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.","aliases":["CVE-2026-12259","GHSA-5wp5-5229-5g6q","GHSA-gf32-cmjh-8m9v","PYSEC-2026-3729"],"modified":"2026-09-10T11:25:57.355843699Z","published":"2026-08-22T14:12:39.360Z","database_specific":{"cwe_ids":["CWE-494"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63310.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63310.json"},{"type":"ADVISORY","url":"https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63310"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nltk/nltk","events":[{"introduced":"0"},{"fixed":"4154eb85e832f266660a09286c7e37e308292284"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.9.3"}],"source":["AFFECTED_FIELD","CPE_RANGE"],"cpe":"cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*"}}],"versions":["v3.9.2","3.9.2","3.9.1","3.9","3.8.2","3.8.1","3.8","3.7","3.6.7","3.6.6","3.6.5","3.6.2","3.6.1","3.6","3.5","3.5b1","3.4.4","3.4.3","3.4.1","3.4","3.3","3.2.5","3.2.4","3.2.3","3.2.2","3.2.1","3.2","3.1","3.0.5","3.0.4","3.0.3","3.0.2","3.0.0b1","3.0a4","2.0.1rc4","2.0.1rc3","2.0.1rc2","2.0.1rc1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63310.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}