CVE-2026-81725
NLTK before 3.10.3 Regular Expression Denial of Service via Pl196xCorpusReader
Description
NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the read_block method through public APIs like words() and tagged_words() to force repeated rescans and achieve near-quadratic runtime growth.
No summary for this CVE yet.
CVSS Vector Breakdown
Exploitability
AV:NAttack VectorNetwork
AC:HAttack ComplexityHigh
PR:NPrivileges RequiredNone
UI:NUser InteractionNone
Scope
S:UScopeUnchanged
Impact
C:NConfidentialityNone
I:NIntegrityNone
A:LAvailabilityLow
Weaknesses
Affected Products
nltk
oss-projectaka nltk/nltk
nltkLibrary
AI / ML / ml-frameworkExploitability
Official Patch Available
Attack Graph
Products CVE Techniques Tactics
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MITRE ATT&CK
1 technique Impact
References
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