CVEvulnerability
CVE-2026-66393
8.7 HIGH
Official page ↗
- Status
- Analyzed
- Published
- 2026-08-22
- Last modified
- 2026-10-14
- Assigner
- [email protected]
- CVSS 4.0 ([email protected])
- 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- CVSS 3.1 ([email protected])
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weaknesses
- CWE-674
Description
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.
Affected configurations
• nltk nltk (< 3.9.4)
Related
Weakness · CWE (1)
- CWE-674 Uncontrolled Recursion weakness
References
- https://github.com/nltk/nltk/security/advisories/GHSA-rf74-v2fm-23pw Exploit, Mitigation, Vendor Advisory
- https://www.vulncheck.com/advisories/nltk-before-denial-of-service-via-jsontaggeddecoder Third Party Advisory
- https://github.com/nltk/nltk/security/advisories/GHSA-rf74-v2fm-23pw Exploit, Mitigation, Vendor Advisory