Staging Environment: Content and features may be unstable or change without notice.
Advisory details: github_osv / GHSA-crp9-r7rq-c8cg
Advisory ID github_osv/GHSA-crp9-r7rq-c8cg
Aliases
Summary Duplicate Advisory: pathsec SSRF protection can be bypassed when a proxy is configured ## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-6ww7-3frv-cqxh. This link is maintained to preserve external references. ## Original 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.
Status Published
Exploitability 0.5
Weighted Severity 7.8
Risk 3.9
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (1)
CWE-918 Server-Side Request Forgery (SSRF)
System Score Found at
cvssv3.1 7.5 https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-crp9-r7rq-c8cg/GHSA-crp9-r7rq-c8cg.json
cvssv4 8.7 https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-crp9-r7rq-c8cg/GHSA-crp9-r7rq-c8cg.json
generic_textual HIGH
Reference id Reference type URL
https://github.com/nltk/nltk/security/advisories/GHSA-6ww7-3frv-cqxh
https://www.vulncheck.com/advisories/nltk-before-ssrf-protection-bypass-via-proxy
CVE-2026-78682 https://nvd.nist.gov/vuln/detail/CVE-2026-78682
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-crp9-r7rq-c8cg/GHSA-crp9-r7rq-c8cg.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Found at https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-crp9-r7rq-c8cg/GHSA-crp9-r7rq-c8cg.json
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

There are no SSVC decisions available.