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CVE-2026-80206

5.9 · MEDIUM

NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module.

Published Aug 26, 2026CWE-1333EPSS 0.44%

Overview

CVE-2026-80206 is a medium-severity vulnerability. It was published on August 26, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or timeout. An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU saturation that blocks the Python process.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/nltk/nltk/security/advisories/GHSA-w3v8-gmh9-3wv7Refwww.vulncheck.com/advisories/nltk-3.10.2-regular-expression-denial-of-service-via-tgrepGitHubgithub.com/nltk/nltk/security/advisories/GHSA-w3v8-gmh9-3wv7

How CyberStrike helps

Frequently asked questions

What is CVE-2026-80206?

CVE-2026-80206 is a medium-severity vulnerability. It was published on August 26, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-80206?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-80206?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-80206?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-80206 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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