Vulnerability-Lookup

CVE-2025-71408 (GCVE-0-2025-71408)

Vulnerability from cvelistv5 – Published: 2026-07-24 21:07 – Updated: 2026-07-25 10:30 X_Open Source

Title

NLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments

Summary

NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the __main__ block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.

Severity

8.5 (High)


                        
                          CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE

CWE-95 - Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

Assigner

VulnCheck

References

5 references

URL	Tags
https://aydinnyunus.github.io/2026/06/07/command-…	technical-descriptionexploit
https://github.com/nltk/nltk/releases/tag/3.9.3	release-notespatch
https://github.com/nltk/nltk/pull/3465	issue-trackingpatch
https://github.com/nltk/nltk/commit/66f14096d952e…	patch
https://www.vulncheck.com/advisories/nltk-eval-in…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
ntlk	ntlk	Affected: 0 , < 3.9.3 (semver)

Date Public

2025-11-17 00:00

Credits

Yunus AYDIN

Show details on NVD website

JSON

To clipboard

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      "affected": [
        {
          "defaultStatus": "affected",
          "packageURL": "pkg:github/nltk/nltk",
          "product": "ntlk",
          "repo": "https://github.com/nltk/nltk",
          "vendor": "ntlk",
          "versions": [
            {
              "lessThan": "3.9.3",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
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          "value": "Yunus AYDIN"
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        }
      ],
      "metrics": [
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            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
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            "attackRequirements": "NONE",
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            "baseScore": 8.5,
            "baseSeverity": "HIGH",
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            "subAvailabilityImpact": "NONE",
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      "problemTypes": [
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          "descriptions": [
            {
              "cweId": "CWE-95",
              "description": "Improper Neutralization of Directives in Dynamically Evaluated Code (\u0027Eval Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-25T10:30:02.196Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "Researcher Disclosure",
          "tags": [
            "technical-description",
            "exploit"
          ],
          "url": "https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/"
        },
        {
          "name": "NLTK 3.9.3 Release Notes",
          "tags": [
            "release-notes",
            "patch"
          ],
          "url": "https://github.com/nltk/nltk/releases/tag/3.9.3"
        },
        {
          "name": "Pull Request",
          "tags": [
            "issue-tracking",
            "patch"
          ],
          "url": "https://github.com/nltk/nltk/pull/3465"
        },
        {
          "name": "Patch Commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "NLTK \u003c 3.9.3 Eval Injection via collocations.py Command-Line Arguments",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2025-71408",
    "datePublished": "2026-07-24T21:07:49.610Z",
    "dateReserved": "2026-07-24T20:57:08.784Z",
    "dateUpdated": "2026-07-25T10:30:02.196Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-71408",
      "date": "2026-07-25",
      "epss": "0.00158",
      "percentile": "0.05359"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-71408\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2026-07-24T22:16:50.063\",\"lastModified\":\"2026-07-24T22:16:50.063\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the __main__ block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.\"}],\"affected\":[{\"source\":\"disclosure@vulncheck.com\",\"affectedData\":[{\"vendor\":\"ntlk\",\"product\":\"ntlk\",\"defaultStatus\":\"affected\",\"repo\":\"https://github.com/nltk/nltk\",\"packageURL\":\"pkg:github/nltk/nltk\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"3.9.3\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/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\",\"baseScore\":8.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-95\"}]}],\"references\":[{\"url\":\"https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/nltk/nltk/pull/3465\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/nltk/nltk/releases/tag/3.9.3\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments\",\"source\":\"disclosure@vulncheck.com\"}]}}"
  }
}

GHSA-848C-C2CX-J7QX

Vulnerability from github – Published: 2026-07-25 00:31 – Updated: 2026-07-25 00:31

Details

NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the main block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

8.5 (High)


                  
                    CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2025-71408"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-95"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-24T22:16:50Z",
    "severity": "HIGH"
  },
  "details": "NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the __main__ block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.",
  "id": "GHSA-848c-c2cx-j7qx",
  "modified": "2026-07-25T00:31:47Z",
  "published": "2026-07-25T00:31:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71408"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/pull/3465"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac"
    },
    {
      "type": "WEB",
      "url": "https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/releases/tag/3.9.3"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/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",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2025-71408 (GCVE-0-2025-71408)

GHSA-848C-C2CX-J7QX

Tags

Sightings

Nomenclature