CVE-2026-78681
NLTK before 3.10.3 Entity Expansion DoS via ElementTree
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-776 |
| Vendor | nltk |
| Product | nltk |
| Published | Aug 25, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
nltk / nltk
0 < 3.10.3