CVE-2026-66393

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Source
https://cve.org/CVERecord?id=CVE-2026-66393
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66393.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-66393
Aliases
Downstream
Related
Published
2026-08-22T14:12:42Z
Modified
2026-09-03T16:25:58Z
Severity
  • 8.7 (High) CVSS_V4 - 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 CVSS Calculator
Summary
NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder
Details

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.

Database specific 
{
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
        "CWE-674"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66393.json"
}
References

Affected packages

Git / github.com/nltk/nltk

Affected ranges

Type
GIT
Repo
https://github.com/nltk/nltk
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
ad9c96ba00a16923ffe917eacf63f1707bfa2d08
Database specific
Show details 
{
    "cpe": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "3.9.4"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "CPE_RANGE"
    ]
}

Affected versions

2.*
2.0.1rc1
2.0.1rc2
2.0.1rc3
2.0.1rc4
3.*
3.0.0b1
3.0.2
3.0.3
3.0.4
3.0.5
3.0a4
3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.3
3.4
3.4.1
3.4.3
3.4.4
3.5
3.5b1
3.6
3.6.1
3.6.2
3.6.5
3.6.6
3.6.7
3.7
3.8
3.8.1
3.8.2
3.9
3.9.1
3.9.2
3.9.3
v3.*
v3.9.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66393.json"