{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63310","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-07-16T12:13:18.733Z","datePublished":"2026-08-22T14:12:39.360Z","dateUpdated":"2026-08-22T14:12:39.360Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-08-22T14:12:39.360Z"},"datePublic":"2026-08-07T00:00:00.000Z","title":"NLTK before 3.9.3 Missing Post-Download Integrity Verification","descriptions":[{"lang":"en","value":"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."}],"problemTypes":[{"descriptions":[{"lang":"en","description":"Download of Code Without Integrity Check","cweId":"CWE-494","type":"CWE"}]}],"affected":[{"vendor":"nltk","product":"nltk","defaultStatus":"unaffected","packageURL":"pkg:pypi/nltk","versions":[{"version":"0","status":"affected","versionType":"semver","lessThan":"3.9.3"},{"version":"3.9.3","status":"unaffected","versionType":"semver"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*","versionEndExcluding":"3.9.3"}]}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":9.3,"baseSeverity":"CRITICAL","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS"},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.1,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H","version":"3.1"},"format":"CVSS"}],"references":[{"url":"https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q","tags":["vendor-advisory"],"name":"GitHub Security Advisory (GHSA-5wp5-5229-5g6q)"},{"name":"VulnCheck Advisory: NLTK before 3.9.3 Missing Post-Download Integrity Verification","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"}],"x_generator":{"engine":"vulncheck-endgame"}}}}