{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-78683",
        "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "state": "PUBLISHED",
        "assignerShortName": "VulnCheck",
        "dateReserved": "2026-08-25T01:17:12.263Z",
        "datePublished": "2026-08-25T01:30:39.451Z",
        "dateUpdated": "2026-08-25T01:30:39.451Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
                "shortName": "VulnCheck",
                "dateUpdated": "2026-08-25T01:30:39.451Z"
            },
            "datePublic": "2026-08-11T00:00:00.000Z",
            "title": "NLTK before 3.10.0 Remote Code Execution via Unsafe Pickle Deserialization",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/parse/transitionparser.py). The method calls pickle_load() with the default restricted=False, routing deserialization through WarningUnpickler, which does not override find_class() and therefore permits arbitrary class resolution. When an application loads an attacker-crafted model file, embedded pickle gadget chains execute arbitrary Python code with the privileges of the user running the application. NLTK provides a RestrictedUnpickler for safe deserialization, but it is not used by production code paths. Fixed in 3.10.0."
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "Deserialization of Untrusted Data",
                            "cweId": "CWE-502",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "nltk",
                    "product": "nltk",
                    "defaultStatus": "unaffected",
                    "packageURL": "pkg:pypi/nltk",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "3.10.0"
                        },
                        {
                            "version": "3.10.0",
                            "status": "unaffected",
                            "versionType": "semver"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "3.10.0"
                                }
                            ]
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "cvssV4_0": {
                        "version": "4.0",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H",
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "PASSIVE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnAvailabilityImpact": "HIGH",
                        "subConfidentialityImpact": "HIGH",
                        "subIntegrityImpact": "HIGH",
                        "subAvailabilityImpact": "HIGH",
                        "baseScore": 9.4,
                        "baseSeverity": "CRITICAL"
                    }
                },
                {
                    "format": "CVSS",
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "privilegesRequired": "NONE",
                        "userInteraction": "REQUIRED",
                        "scope": "CHANGED",
                        "confidentialityImpact": "HIGH",
                        "integrityImpact": "HIGH",
                        "availabilityImpact": "HIGH",
                        "baseScore": 9.6,
                        "baseSeverity": "CRITICAL"
                    }
                }
            ],
            "references": [
                {
                    "url": "https://github.com/nltk/nltk/security/advisories/GHSA-rhp5-r9x4-f5g2",
                    "tags": [
                        "vendor-advisory"
                    ],
                    "name": "GitHub Security Advisory (GHSA-rhp5-r9x4-f5g2)"
                },
                {
                    "name": "VulnCheck Advisory: NLTK before 3.10.0 Remote Code Execution via Unsafe Pickle Deserialization",
                    "tags": [
                        "third-party-advisory"
                    ],
                    "url": "https://www.vulncheck.com/advisories/nltk-before-remote-code-execution-via-unsafe-pickle-deserialization"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "ekaf",
                    "type": "analyst"
                }
            ],
            "x_generator": {
                "engine": "vulncheck-endgame"
            }
        }
    }
}