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TI-2026-45157 Aliases CVE-2026-63312GHSA-x5ph-mj9p-rfr8

NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read

Priority HIGH 77CWE-22Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-22 and the CVSS impact.

Summary

NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00651 51st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial nltk (nltk): 3.10.0nltk (PyPI): 3.10.0Red Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
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 3.10.03.10.0Patch availableCNA
—nltk (PyPI)before 3.10.03.10.0Patch availableGHSA-x5ph-mj9p-rfr8
  • nltk Vendornltk Affected before 3.10.0 Fixed in 3.10.0 Patch available CNA
  • nltk (PyPI) Vendor— Affected before 3.10.0 Fixed in 3.10.0 Patch available GHSA-x5ph-mj9p-rfr8

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*before 3.10.0Vulnerablenltk
  • cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* Versions before 3.10.0 Vulnerable ·nltk

Remediation

  • Fix · CNA nltk (nltk) Fixed in 3.10.0
  • Fix · GHSA-x5ph-mj9p-rfr8 nltk (PyPI) Fixed in 3.10.0 Advisory →

Fixed in the same release

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

  • Release ·

    nltk 3.10.0

    5 records Highest priority Priority HIGH 3 HIGH, 1 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-44528 NLTK before 3.10.0 Insecure Default Configuration in pathsec.pyPriority HIGH 77
    • TI-2026-44525 NLTK 3.9.4 Path Traversal via FrameNet and NKJP ReadersPriority HIGH 69
    • TI-2026-46953 NLTK before 3.10.0 Arbitrary File Read via FileSystemPathPointerPriority MEDIUM 64
    Show all 5 records →

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Lightspeed CoreAffectedNo fix yet
Red Hat Ansible Automation Platform 2AffectedNo fix planned: Will not fix
Not affected: 3 products
  • Exploit Intelligence
  • OpenShift Lightspeed
  • Red Hat OpenShift AI (RHOAI)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-63312
  2. 2026-10-03 Alias added: GHSA-x5ph-mj9p-rfr8
  3. 2026-10-14 EPSS moved to the 50th–90th percentile

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