CVE-2026-12372
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Summary
A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the current develop branch. The nltk.pathsec.validate_network_url() function, intended to prevent SSRF by rejecting internal network addresses, fails to reject IPs in the RFC 6598 shared address space (100.64.0.0/10). This occurs because Python's ipaddress module does not classify such addresses as is_private or is_global, and the current guard only checks is_private and a few explicit categories. An attacker who can influence a URL passed to NLTK's network-loading helpers can exploit this vulnerability to make a strict-mode application send requests to shared-address-space hosts, potentially exposing non-public infrastructure reachable from the application host. The impact is limited to SSRF-style confidentiality exposure, with no code execution claimed.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| nltk | nltk/nltk | unspecified <= latest | affected |
Weaknesses
- CWE-918: CWE-918 Server-Side Request Forgery (SSRF)
References
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