Quadratic CPU Exhaustion Vulnerability in NLTK by NLTK Developers
CVE-2026-81723

6.3MEDIUM

Key Information:

Vendor

Nltk

Status
Nltk
Vendor
CVE Published:
27 August 2026

What is CVE-2026-81723?

NLTK is impacted by a vulnerability in the XMLCorpusView component, where improper handling of XML fragments can lead to excessive CPU utilization. This occurs when the library processes malformed XML corpus files, forcing a repetitive rescan of the data with each 1 KiB block read. Attackers can exploit this flaw, leading to significant degradation of performance and potential denial of service for applications that utilize readers such as BNCCorpusReader.

Affected Version(s)

nltk 0 < 3.10.3

nltk 3.10.3

References

https://github.com/nltk/nltk/security/advisories/GHSA-vp2...
vendor-advisory
https://www.vulncheck.com/advisories/nltk-before-3.10.3-q...
third-party-advisory

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

ibfavas
.