Inefficient regular expression complexity in Natural Language Toolkit - CVE-2026-54295
Published: August 7, 2026
Vulnerability identifier: #VU141243
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-54295
CWE-ID: CWE-1333
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 regular expression complexity in the ReviewsCorpusReader FEATURES regex when parsing a crafted bracket-less review line. A remote attacker can supply a specially crafted reviews corpus line to cause a denial of service.
A single crafted line can hang the reviews(), features(), and sents() processing paths.
Affected software
Natural Language Toolkit
How to mitigate CVE-2026-54295
Install security update from vendor's website.
Natural Language Toolkit - update to 3.10.0