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TI-2026-54693 Aliases CVE-2026-78681GHSA-97qj-x29f-37w7

NLTK before 3.10.3 Entity Expansion DoS via ElementTree

Priority MEDIUM 44CWE-776Published · Updated

Key facts

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

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

Summary

NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00521 44th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed nltk (nltk): 3.10.3nltk (PyPI): 3.10.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
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 3.10.33.10.3Patch availableCNA
—nltk (PyPI)before 3.10.33.10.3Patch availableGHSA-97qj-x29f-37w7
  • nltk Vendornltk Affected before 3.10.3 Fixed in 3.10.3 Patch available CNA
  • nltk (PyPI) Vendor— Affected before 3.10.3 Fixed in 3.10.3 Patch available GHSA-97qj-x29f-37w7

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*before 3.10.3Vulnerablenltk
  • cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* Versions before 3.10.3 Vulnerable ·nltk

Remediation

  • Fix · CNA nltk (nltk) Fixed in 3.10.3
  • Fix · GHSA-97qj-x29f-37w7 nltk (PyPI) Fixed in 3.10.3 Advisory →

Fixed in the same release

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

  • Release ·

    nltk 3.10.3

    7 records Highest priority Priority HIGH 6 HIGH, 1 MEDIUM

    Other records, highest priority first

    • TI-2026-55173 NLTK before 3.10.3 JVM Argument Injection via Per-Call OptionsPriority HIGH 81
    • TI-2026-55155 NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle DeserializationPriority HIGH 81
    • TI-2026-55172 NLTK 3.10.2 Path Traversal via corpus-reader constructorsPriority HIGH 77
    Show all 7 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-78681
  2. 2026-10-03 Alias added: GHSA-97qj-x29f-37w7

References

Exploit 1

Advisory 1

Other 4

  • 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