VulnerabilityAnalyzed

CVE-2026-78682

HIGH 8.7EPSS 0.43%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.43%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 4.0: 8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.43% probability · 38th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-918
Affected: nltk/nltk
Source: disclosure@vulncheck.com

EPSS trend

EPSS 0.4% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxhExploit, Vendor Advisory
https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxyThird Party Advisory
https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxhExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.