CVE-2026-126297

HIGH 7.5

NLTK before 3.10.4 CPU Denial of Service via ConllCorpusReader srl_instances

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-400
Vendor	nltk
Product	nltk
Published	Nov 13, 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 < 3.10.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/nltk/nltk/security/advisories/GHSA-v8f3-6phw-6mh9 vulncheck.com: https://www.vulncheck.com/advisories/nltk-before-3.10.4-cpu-denial-of-service-via-conllcorpusreader-srl-instances

Credits

🔍 manus-use