CVE-2026-80206 (GCVE-0-2026-80206)

Vulnerability from cvelistv5 – Published: 2026-08-26 10:28 – Updated: 2026-08-26 12:52
VLAI
Title
NLTK 3.10.2 Regular Expression Denial of Service via tgrep
Summary
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.
Severity
8.2 (High)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-26 12:52 UTC
CWE
  • CWE-1333 - Inefficient Regular Expression Complexity
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 8186 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
nltk nltk Affected: 0 , < 3.10.3 (semver)
Unaffected: 3.10.3 (semver)
    cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-08-12 00:00
Credits
infycore ekaf agent-kira
Show details on NVD website
To clipboard 

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