NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user-supplied regular expressions without validation or timeout. Attackers can supply crafted regex patterns that cause catastrophic backtracking, resulting in indefinite CPU saturation and denial of service to all users of the Python process.
History

Tue, 01 Sep 2026 23:30:00 +0000

Type Values Removed Values Added
References

Fri, 28 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 27 Aug 2026 18:00:00 +0000

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References
Metrics threat_severity

None

threat_severity

Important


Wed, 26 Aug 2026 10:30:00 +0000

Type Values Removed Values Added
Description NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user-supplied regular expressions without validation or timeout. Attackers can supply crafted regex patterns that cause catastrophic backtracking, resulting in indefinite CPU saturation and denial of service to all users of the Python process.
Title NLTK before 3.10.0 ReDoS via Text.findall() unvalidated regex
First Time appeared Nltk
Nltk nltk
Weaknesses CWE-1333
CPEs cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
Vendors & Products Nltk
Nltk nltk
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-08-26T10:28:14.352Z

Updated: 2026-09-01T22:06:44.235Z

Reserved: 2026-08-25T23:15:39.155Z

Link: CVE-2026-80205

cve-icon Vulnrichment

Updated: 2026-09-01T22:06:44.235Z

cve-icon NVD

Status : Modified

Published: 2026-08-26T11:16:39.950

Modified: 2026-09-03T05:15:15.430

Link: CVE-2026-80205

cve-icon Redhat

Severity : Important

Publid Date: 2026-08-26T10:28:14Z

Links: CVE-2026-80205 - Bugzilla