CVE-2026-126297

EUVD-2026-125224
NLTK before 3.10.4 contains a quadratic-time denial of service vulnerability in ConllCorpusReader._get_srl_instances that allows remote attackers to exhaust CPU through nested span rescans. Attackers can supply a crafted CoNLL SRL corpus with many predicates and span columns, placing the head span last, to pin a core for minutes.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 48.33%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
nltknltk
𝑥
< 3.10.4
CNA
Common Weakness Enumeration
References
https://github.com/nltk/nltk/security/advisories/GHSA-v8f3-6phw-6mh9
https://www.vulncheck.com/advisories/nltk-before-3.10.4-cpu-denial-of-service-via-conllcorpusreader-srl-instances