Server-Side Request Forgery (SSRF) Affecting nltk package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-ECHOLATEST-NLTK-18601910
- published10 Aug 2026
- disclosed9 Aug 2026
Introduced: 9 Aug 2026
NewCVE-2026-12372 (opens in a new tab)How to fix?
There is no fixed version for Echo:latest nltk.
NVD Description
Note: Versions mentioned in the description apply only to the upstream nltk package and not the nltk package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
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.