CVE-2026-78681
Published:August 25, 2026
Updated:August 25, 2026
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.
Affected Packages
nltk (CONDA):
Affected version(s) >=2.0.3 <3.10.3Fix Suggestion:
Update to version 3.10.3nltk (PYTHON):
Affected version(s) >=0.8 <3.10.3Fix Suggestion:
Update to version 3.10.3Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
EPSS
Base Score:
0.28