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.
Metrics
Affected Vendors & Products
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History
Fri, 04 Sep 2026 14:15:00 +0000
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Nltk nltk
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| CPEs | cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:* | |
| Vendors & Products |
Nltk nltk
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Wed, 12 Aug 2026 18:30:00 +0000
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ssvc
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Mon, 10 Aug 2026 01:15:00 +0000
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Nltk
Nltk nltk/nltk |
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| Vendors & Products |
Nltk
Nltk nltk/nltk |
Mon, 10 Aug 2026 00:15:00 +0000
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threat_severity
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cvssV3_1
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Sun, 09 Aug 2026 23:00:00 +0000
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| 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. | |
| Title | Server-Side Request Forgery (SSRF) in nltk/nltk | |
| Weaknesses | CWE-918 | |
| References |
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| Metrics |
cvssV3_0
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Status: PUBLISHED
Assigner: @huntr_ai
Published: 2026-08-09T22:45:52.799Z
Updated: 2026-08-12T17:48:54.679Z
Reserved: 2026-06-16T06:05:39.765Z
Link: CVE-2026-12372
Updated: 2026-08-12T17:46:50.952Z
Status : Analyzed
Published: 2026-08-09T23:16:35.793
Modified: 2026-09-04T13:59:06.927
Link: CVE-2026-12372