{"id":"CVE-2026-78682","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-78682","summary":"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…","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.","published":"2026-08-25T02:16:52.890","modified":"2026-08-25T02:16:52.890","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxh"},{"type":"WEB","url":"https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxy"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-08-25T02:16:52.890"}}