Server-Side Request Forgery (SSRF) in nltk/nltk

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-12372
StatePUBLISHED
Assigner@huntr_ai
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-09 23:16:35 UTC
Updated2026-08-09 23:16:35 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.0 3.7 LOW from [email protected]

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-918 | CWE-918 CWE-918 Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.0[email protected]Secondary3.7LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
3.0CNADECLARED3.7LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nltk Nltk/nltk affected unspecified latest custom Not specified

References

ReferenceSourceLinkTags
huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491db [email protected] huntr.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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