CVE-2026-12372
A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the current develop branch.
Does this matter?
Lower severity and a low EPSS score (0.26%). Track it; it rarely justifies an emergency change on its own.
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 3.0
- 3.7 LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- EPSS
- 0.26% probability · 18th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-918
- Affected
- nltk/nltk
- Source
- security@huntr.dev
References
- https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491dbPermissions Required
- https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491dbPermissions Required
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.