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TI-2026-49337 Aliases CVE-2026-70626GHSA-r6gq-whwq-mvg9

NLTK before 3.9.4 Symlink Escape via CorpusReader

Priority HIGH 70CWE-59Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

NLTK versions before 3.9.4 contain a symlink escape vulnerability in CorpusReader.open() that allows local attackers to read arbitrary files outside the corpus root. The vulnerability exists because path validation is lexical and does not account for symlink resolution, enabling attackers to place symlinks inside the corpus root to access files outside the intended boundary.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.002 9th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed nltk (nltk): 3.9.4nltk (PyPI): 3.9.4

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

VendorProductAffected versionsFixed inStatusSource
nltknltkbefore 3.9.43.9.4Patch availableCNA
—nltk (PyPI)before 3.9.43.9.4Patch availableGHSA-r6gq-whwq-mvg9
  • nltk Vendornltk Affected before 3.9.4 Fixed in 3.9.4 Patch available CNA
  • nltk (PyPI) Vendor— Affected before 3.9.4 Fixed in 3.9.4 Patch available GHSA-r6gq-whwq-mvg9

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*before 3.9.4Vulnerablenltk
  • cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* Versions before 3.9.4 Vulnerable ·nltk

Remediation

  • Fix · CNA nltk (nltk) Fixed in 3.9.4
  • Fix · GHSA-r6gq-whwq-mvg9 nltk (PyPI) Fixed in 3.9.4 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    nltk 3.9.4

    2 records Highest priority Priority HIGH 2 HIGH

    Other records, highest priority first

    • TI-2026-47152 NLTK before 3.9.4 Denial of Service via JSONTaggedDecoderPriority HIGH 77
    Show all 2 records →

Vendor assessments

Red Hat

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

Not affected: 5 products
  • Exploit Intelligence
  • Lightspeed Core
  • OpenShift Lightspeed
  • Red Hat Ansible Automation Platform 2
  • Red Hat OpenShift AI (RHOAI)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-70626
  2. 2026-10-03 Alias added: GHSA-r6gq-whwq-mvg9

References

Exploit 1

Advisory 1

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

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences