Low severity · published Aug 27, 2026
CVE-2026-81723
NLTK before 3.10.3 Quadratic CPU Exhaustion via XMLCorpusView
3.7
CVSS
0.3%
EPSS
No
On KEV
Description
NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView._read_xml_fragment() that rescans accumulated XML fragments on every 1 KiB block read. Attackers can provide malformed XML corpus files to cause severe CPU consumption and denial of service through affected readers like BNCCorpusReader.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 20% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NL
nltk · nltk
before 3.10.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-81723
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-81723
github.com
https://github.com/nltk/nltk/security/advisories/GHSA-vp2x-qp44-57v7
www.vulncheck.com
https://www.vulncheck.com/advisories/nltk-before-3.10.3-quadratic-cpu-exhaustion-via-xmlcorpusview
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