Vulnerability Details CVE-2026-78681
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 19.9%
CVSS Severity
CVSS v3 Score 7.5