CVE-2026-126300

EUVD-2026-125221
NLTK from 3.2.5 before 3.10.4 contains an algorithmic complexity vulnerability in TreebankWordTokenizer.span_tokenize that allows remote attackers to cause quadratic CPU consumption through repeated list.pop(0) calls. Attackers can submit long runs of double-quote characters to services span-tokenizing untrusted text, exhausting a CPU core and degrading availability.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 44.01%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
nltknltk
3.2.5 ≤
𝑥
< 3.10.4
CNA
Common Weakness Enumeration
References
https://github.com/nltk/nltk/security/advisories/GHSA-ffr9-mgrr-wcvr
https://www.vulncheck.com/advisories/nltk-from-3.2.5-before-3.10.4-cpu-exhaustion-via-treebankwordtokenizer-span-tokenize