Vulnerability Description
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.
CVSS Score
LOW
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nltk | Nltk | 3.9.4 |
Related Weaknesses (CWE)
References
- https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491dbPermissions Required
- https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491dbPermissions Required
FAQ
What is CVE-2026-12372?
CVE-2026-12372 is a vulnerability with a CVSS score of 3.7 (LOW). 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 re...
How severe is CVE-2026-12372?
CVE-2026-12372 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-12372?
Check the references section above for vendor advisories and patch information. Affected products include: Nltk Nltk.