CVE-2026-66393 (GCVE-0-2026-66393)

Vulnerability from cvelistv5 – Published: 2026-08-22 14:12 – Updated: 2026-08-26 17:55
VLAI
Title
NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder
Summary
NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() that allows attackers to cause denial of service by supplying deeply nested JSON structures. Attackers can craft JSON payloads exceeding the recursion limit to trigger an unhandled RecursionError that crashes the Python process.
Severity
8.7 (High)
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
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-26 17:54 UTC
CWE
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 6249 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
nltk nltk Affected: 0 , < 3.9.4 (semver)
Unaffected: 3.9.4 (semver)
    cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-03-18 00:00
Credits
ZeroXJacks
Show details on NVD website
To clipboard 

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