{"cve":"CVE-2026-78682","nvd":{"published":"2026-08-25T02:16:52.890","modified":"2026-10-12T21:10:00.227","status":"Analyzed","description":"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.","cvss_v4":{"vector":"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","score":8.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","score":7.5},"cwes":["CWE-918"],"references":["https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxh","https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxy","https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxh"],"products":["nltk:nltk"],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-78682","score":0.00435,"percentile":0.37481,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-6ww7-3frv-cqxh","url":"https://osv.dev/vulnerability/GHSA-6ww7-3frv-cqxh","summary":"NLTK: pathsec SSRF protection can be bypassed when a proxy is configured","modified":"2026-09-08T16:45:04.147588108Z","packages":[{"ecosystem":"PyPI","name":"nltk","purl":"pkg:pypi/nltk","ranges":["<3.10.3"],"fixed":["3.10.3"]}]},{"id":"PYSEC-2026-3733","url":"https://osv.dev/vulnerability/PYSEC-2026-3733","summary":"","modified":"2026-09-01T09:15:03.610403607Z","packages":[{"ecosystem":"PyPI","name":"nltk","purl":"pkg:pypi/nltk","ranges":["<3.10.3"],"fixed":["3.10.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}