Inefficient Algorithmic Complexity in Natural Language Toolkit - CVE-2026-81723
Published: August 15, 2026 / Updated: September 14, 2026
Vulnerability identifier: #VU142778
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-81723
CWE-ID: CWE-407
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient algorithmic complexity in XMLCorpusView._read_xml_fragment() when processing attacker-controlled XML corpus files. A remote attacker can supply a malformed XML file to cause a denial of service.
The issue is triggered by quadratic rescanning of the accumulated fragment buffer, and no user interaction is required.
Affected software
Natural Language Toolkit
How to mitigate CVE-2026-81723
Install security update from vendor's website.
Natural Language Toolkit - update to 3.10.2