Disclosure 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 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.
Source-reported weakness categories
CWE-918
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-78682
Open original source · Updated Oct 08, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| nltk | nltk | * {"versionEndExcluding":"3.10.3"} |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Exploit, Vendor Advisory
- www.vulncheck.com — Third Party Advisory
- github.com — Exploit, Vendor Advisory
PUBLISHED 2026-08-24T22:16:52-04:00
MODIFIED 2026-10-08T12:17:44-04:00
INGESTED 2026-10-10T20:50:36-04:00