TI-2026-10625 Aliases CVE-2026-12372 GHSA-2jhm-w3mp-jcwr

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

MEDIUM 51CWE-918Published 2026-08-09 · Updated 2026-08-12

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Information disclosure
Confidentiality · integrity · availability: Low · None · None
Fix status: Partial Red Hat: 5 without a fix

Attack profile from CVSS 3.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-918 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.0026 17th percentileScored 2026-11-07

Fix Partial nltk (PyPI): 3.10.0Red Hat: 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
nltk	nltk/nltk	up to latest	—	No fix listed	CNA
—	nltk (PyPI)	before 3.10.0	3.10.0	Patch available	GHSA-2jhm-w3mp-jcwr

nltk/nltk Vendornltk Affected up to latest Fixed in — No fix listed CNA
nltk (PyPI) Vendor— Affected before 3.10.0 Fixed in 3.10.0 Patch available GHSA-2jhm-w3mp-jcwr

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:nltk:nltk:3.9.4:::::::*	3.9.4	Vulnerable	nltk

cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:* Versions 3.9.4 Vulnerable ·nltk

Remediation

Fix · GHSA-2jhm-w3mp-jcwr nltk (PyPI) Fixed in 3.10.0 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

Product	Status	Plan or fix
Exploit Intelligence	Affected	No fix planned: Out of support scope
Lightspeed Core	Affected	No fix yet: Fix deferred
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix planned: Out of support scope
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-12372
2026-10-03 Alias added: GHSA-2jhm-w3mp-jcwr

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-12372

Other 5

TI-2026-00629 Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading CVSS 3.0CRITICAL 10.0
TI-2025-12800 Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution CVSS 3.0CRITICAL 10.0
TI-2026-55173 NLTK before 3.10.3 JVM Argument Injection via Per-Call Options CVSS 4.0CRITICAL 9.3
TI-2026-55155 NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization CVSS 4.0CRITICAL 9.3
TI-2026-56370 nltk PorterStemmer before 3.10.3 Quadratic-time DoS CVSS 4.0HIGH 8.7
TI-2026-55172 NLTK 3.10.2 Path Traversal via corpus-reader constructors CVSS 4.0HIGH 8.8

See all 41 →

Sources

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