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 configure
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
Affected packages
No package-level mapping for this advisory.
Exploit signal
- Known exploited (CISA KEV)
- No
- EPSS score
- —
- EPSS percentile
- —
EPSS is the probability a CVE is exploited in the wild; percentile is its rank among all CVEs.
Sources
- https://www.cve.org/CVERecord?id=CVE-2026-78682
- https://github.com/cveproject/cvelistv5/tree/main/cves/2026/78xxx/cve-2026-78682.json
- https://github.com/nltk/nltk/security/advisories/ghsa-6ww7-3frv-cqxh
- https://nvd.nist.gov/vuln/detail/cve-2026-78682
- https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxy
Structured record: https://ubuntu.com/security/CVE-2026-78682
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