High [CVE-2026-80205] Denial of Service via unvalidated regular expressions
This high-severity Red Hat Linux advisory covers CVE-2026-80205 affecting Exploit Intelligence, Lightspeed Core, OpenShift Lightspeed.
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Summary
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. A flaw was found in NLTK.
These methods accept user-supplied regular expressions without validation, allowing an attacker to provide crafted patterns that cause catastrophic backtracking. The functions process unvalidated, user-supplied regular expressions without evaluation timeouts.
An unauthenticated remote attacker can exploit this by supplying a specially crafted regex pattern designed to trigger catastrophic backtracking. This causes CPU resource exhaustion within the hosting Python process context, leading to a denial-of-service condition for all dependent services running within that execution environment.
Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-1333.
Affected Red Hat products: Exploit Intelligence; Lightspeed Core; OpenShift Lightspeed; Red Hat Ansible Automation Platform 2; Red Hat OpenShift AI (RHOAI). Red Hat lists OpenShift Lightspeed as not affected.
- < 3.10.0
Official advisory · high-confidence parse· fetched 55 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 55 minutes ago·verify at source
Mitigation checklist
- Sanitize all untrusted input passed to `Text.findall()` or `TokenSearcher.findall()` to prevent execution of arbitrary or unvalidated regular expressions, or enforce execution timeouts via worker process isolation to bound CPU consumption.
Official advisory · high-confidence parse· fetched 55 minutes ago·verify at source
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