CVE-2026-78682
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.
Not on KEV
Not in CISA's Known Exploited Vulnerabilities catalogue as of the last daily pull. Absence is not proof of safety.
0%
Chance of exploitation in the next 30 days, 17th percentile of all CVEs. A forecast; KEV outranks it.
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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No exposure census on this CVE's dispatches.
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