{"id":"CVE-2026-78682","summary":"NLTK before 3.10.3 SSRF Protection Bypass via Proxy","details":"NLTK before 3.10.3 contains a server-side request forgery vulnerability in nltk.pathsec.urlopen (and callers nltk.data.load, nltk.downloader.Downloader.index/download) when an HTTP proxy is configured. pathsec.urlopen validates the requested hostname locally, but proxy-handler inheritance disables the safe HTTP/HTTPS handlers so the actual fetch is performed by the proxy against a destination that is never re-validated. An attacker can supply a validated public URL that the proxy forwards to an internal loopback-only service, allowing disclosure of internal HTTP resources, loading of forged downloader indexes, and installation of attacker-chosen package content.","aliases":["GHSA-6ww7-3frv-cqxh","PYSEC-2026-3733"],"modified":"2026-09-02T03:47:27.494875602Z","published":"2026-08-25T01:30:38.486Z","database_specific":{"cwe_ids":["CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/78xxx/CVE-2026-78682.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/78xxx/CVE-2026-78682.json"},{"type":"ADVISORY","url":"https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-78682"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxy"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nltk/nltk","events":[{"introduced":"0"},{"fixed":"303f6e2ba8e4548a5f54fd65d86bb5c9a949f1db"}],"database_specific":{"cpe":"cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"3.10.3"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v3.10.2-rc1","v3.10.2","v3.10.1","v.3.10.1","v3.10.1-rc2","v3.10.0-rc2","v3.10.0","v3.10.1-rc1","v3.10.0-rc1","3.9.4","3.9.3","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-2026-78682.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:N/VA:N/SC:N/SI:N/SA:N"}]}