FKIE_CVE-2026-71513

Vulnerability from fkie_nvd - Published: 2026-08-22 14:16 - Updated: 2026-10-14 19:10
Severity
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.
References
disclosure@vulncheck.comhttps://github.com/nltk/nltkProduct
disclosure@vulncheck.comhttps://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124Product
disclosure@vulncheck.comhttps://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805eaPatch
disclosure@vulncheck.comhttps://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypassThird Party Advisory, Patch
Impacted products
Vendor Product Version
nltk nltk *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:pypi/nltk",
          "product": "nltk",
          "vendor": "nltk",
          "versions": [
            {
              "lessThan": "3.10.3",
              "status": "affected",
              "version": "3.10.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "3.10.3",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "disclosure@vulncheck.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "907206A4-3761-4899-9D77-F79C72F6229B",
              "versionEndExcluding": "3.10.3",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load."
    },
    {
      "lang": "es",
      "value": "NLTK anterior a la versi\u00f3n 3.10.3 contiene una vulnerabilidad de ejecuci\u00f3n remota de c\u00f3digo en AllowlistUnpickler que valida solo la cadena del m\u00f3dulo pickle y no el nombre global, permitiendo a los atacantes resolver nombres con puntos mediante la transversalidad de atributos a elementos invocables fuera del espacio de nombres en la lista blanca. Los atacantes pueden crear modelos de analizador de transici\u00f3n no confiables que ejecutan comandos arbitrarios cuando TransitionParser.parse carga el modelo a trav\u00e9s de allowlisted_pickle_load."
    }
  ],
  "id": "CVE-2026-71513",
  "lastModified": "2026-10-14T19:10:00.297",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-71513",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-25T03:56:57.129387Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-22T14:16:33.417",
  "references": [
    {
      "source": "disclosure@vulncheck.com",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/nltk/nltk"
    },
    {
      "source": "disclosure@vulncheck.com",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124"
    },
    {
      "source": "disclosure@vulncheck.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea"
    },
    {
      "source": "disclosure@vulncheck.com",
      "tags": [
        "Third Party Advisory",
        "Patch"
      ],
      "url": "https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass"
    }
  ],
  "sourceIdentifier": "disclosure@vulncheck.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-502"
        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Secondary"
    }
  ]
}



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