Server-Side Request Forgery (SSRF) in nltk/nltk (nltk nltk/nltk)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.26 % · percentile 18 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- @huntr_ai
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-918 — Server-Side Request Forgery
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.0 | LOW 3.7 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N | @huntr_ai |
| CVSS 3.0 | LOW 3.7 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N | NVD · security@huntr.dev (Secondary) |
Advisories
- GHSA-2jhm-w3mp-jcwr — NLTK network URL validation permits SSRF to RFC 6598 shared-address-space hosts
- PYSEC-2026-3955 — 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()`
European references
- ENISA EUVD · EUVD-2026-54961
- GCVE · GCVE-0-2026-12372
Affected configurations (NVD CPE)
cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|---|
| nltk · nltk/nltk | affected unspecified ≤ latest |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |