Common Weakness Enumeration

CWE-502

Allowed

Deserialization of Untrusted Data

Abstraction: Base · Status: Draft

API response cwe.mitre.org

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

5266 vulnerabilities reference this CWE, most recent first.

GHSA-RG8P-9RPG-R32P

Vulnerability from github – Published: 2026-05-26 15:32 – Updated: 2026-06-03 21:30

Details

Mirasvit Full Page Cache Warmer for Magento 2 before version 1.11.12 contains a PHP object injection vulnerability that allows unauthenticated attackers to achieve remote code execution by supplying a crafted serialized PHP object in the CacheWarmer cookie. Attackers can exploit the unrestricted call to PHP's native unserialize() function combined with gadget chains available in Magento and its dependencies to execute arbitrary code on the server.

Severity

9.8 (Critical)


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

9.3 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-45247"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-26T15:16:39Z",
    "severity": "CRITICAL"
  },
  "details": "Mirasvit Full Page Cache Warmer for Magento 2 before version 1.11.12 contains a PHP object injection vulnerability that allows unauthenticated attackers to achieve remote code execution by supplying a crafted serialized PHP object in the CacheWarmer cookie. Attackers can exploit the unrestricted call to PHP\u0027s native unserialize() function combined with gadget chains available in Magento and its dependencies to execute arbitrary code on the server.",
  "id": "GHSA-rg8p-9rpg-r32p",
  "modified": "2026-06-03T21:30:25Z",
  "published": "2026-05-26T15:32:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45247"
    },
    {
      "type": "WEB",
      "url": "https://mirasvit.com/package/changelog/?package=mirasvit/module-cache-warmer"
    },
    {
      "type": "WEB",
      "url": "https://sansec.io/research/mirasvit-cache-warmer-object-injection"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-45247"
    },
    {
      "type": "WEB",
      "url": "https://www.imperva.com/blog/imperva-customers-protected-against-cve-2026-45247-in-mirasvit-full-page-cache-warmer-for-magento"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/mirasvit-cache-warmer-for-magento-php-object-injection"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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"
    }
  ]
}

GHSA-RGG3-PRC9-59MW

Vulnerability from github – Published: 2024-03-28 06:30 – Updated: 2025-05-29 21:31

Details

Deserialization of Untrusted Data vulnerability in Repute Infosystems ARMember.This issue affects ARMember: from n/a through 4.0.26.

Severity

9.0 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2024-30223"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-03-28T05:15:50Z",
    "severity": "CRITICAL"
  },
  "details": "Deserialization of Untrusted Data vulnerability in Repute Infosystems ARMember.This issue affects ARMember: from n/a through 4.0.26.",
  "id": "GHSA-rgg3-prc9-59mw",
  "modified": "2025-05-29T21:31:32Z",
  "published": "2024-03-28T06:30:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-30223"
    },
    {
      "type": "WEB",
      "url": "https://patchstack.com/database/vulnerability/armember-membership/wordpress-armember-plugin-4-0-26-unauthenticated-php-object-injection-vulnerability?_s_id=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RGGG-JP6V-H52J

Vulnerability from github – Published: 2025-12-09 18:30 – Updated: 2025-12-09 18:30

Details

NVIDIA NVTabular for Linux contains a vulnerability in the Workflow component, where a user could cause a deserialization issue. A successful exploit of this vulnerability might lead to code execution, denial of service, information disclosure, and data tampering.

Severity

8.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-33214"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-09T18:15:49Z",
    "severity": "HIGH"
  },
  "details": "NVIDIA NVTabular for Linux contains a vulnerability in the Workflow component, where a user could cause a deserialization issue. A successful exploit of this vulnerability might lead to code execution, denial of service, information disclosure, and data tampering.",
  "id": "GHSA-rggg-jp6v-h52j",
  "modified": "2025-12-09T18:30:45Z",
  "published": "2025-12-09T18:30:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-33214"
    },
    {
      "type": "WEB",
      "url": "https://nvidia.custhelp.com/app/answers/detail/a_id/5739"
    },
    {
      "type": "WEB",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-33214"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RGQ9-FQF5-FV58

Vulnerability from github – Published: 2026-03-12 12:30 – Updated: 2026-04-07 22:14

Summary

SGLang's multimodal generation module is vulnerable to unauthenticated remote code execution through the ZMQ broker

Details

SGLang's multimodal generation module is vulnerable to unauthenticated remote code execution through the ZMQ broker, which deserializes untrusted data using pickle.loads() without authentication.

Severity

9.8 (Critical)


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

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.5.9"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "sglang"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.5.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-3059"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-12T17:38:58Z",
    "nvd_published_at": "2026-03-12T12:15:59Z",
    "severity": "CRITICAL"
  },
  "details": "SGLang\u0027s multimodal generation module is vulnerable to unauthenticated remote code execution through the ZMQ broker, which deserializes untrusted data using pickle.loads() without authentication.",
  "id": "GHSA-rgq9-fqf5-fv58",
  "modified": "2026-04-07T22:14:24Z",
  "published": "2026-03-12T12:30:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sgl-project/sglang/security/advisories/GHSA-3cp7-c6q2-94xr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-3059"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sgl-project/sglang/pull/20904"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sgl-project/sglang"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sgl-project/sglang/blob/main/python/sglang/multimodal_gen/runtime/scheduler_client.py"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sgl-project/sglang/releases/tag/v0.5.10"
    },
    {
      "type": "WEB",
      "url": "https://orca.security/resources/blog/sglang-llm-framework-rce-vulnerabilities"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SGLang\u0027s multimodal generation module is vulnerable to unauthenticated remote code execution through the ZMQ broker"
}

GHSA-RGQ9-RG7J-XM4X

Vulnerability from github – Published: 2025-05-13 03:31 – Updated: 2025-10-22 00:33

Details

SAP NetWeaver Visual Composer Metadata Uploader is vulnerable when a privileged user can upload untrusted or malicious content which, when deserialized, could potentially lead to a compromise of confidentiality, integrity, and availability of the host system.

Severity

9.1 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-42999"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-05-13T01:15:48Z",
    "severity": "CRITICAL"
  },
  "details": "SAP NetWeaver Visual Composer Metadata Uploader is vulnerable when a privileged user can upload untrusted or malicious content which, when deserialized, could potentially lead to a compromise of confidentiality, integrity, and availability of the host system.",
  "id": "GHSA-rgq9-rg7j-xm4x",
  "modified": "2025-10-22T00:33:18Z",
  "published": "2025-05-13T03:31:14Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-42999"
    },
    {
      "type": "WEB",
      "url": "https://me.sap.com/notes/3604119"
    },
    {
      "type": "WEB",
      "url": "https://onapsis.com/blog/active-exploitation-of-sap-vulnerability-cve-2025-31324"
    },
    {
      "type": "WEB",
      "url": "https://url.sap/sapsecuritypatchday"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-42999"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RGV9-Q543-RQG4

Vulnerability from github – Published: 2022-10-03 00:00 – Updated: 2026-05-21 00:22

Summary

Uncontrolled Resource Consumption in FasterXML jackson-databind

Details

In FasterXML jackson-databind before 2.12.7.1 and in 2.13.x before 2.13.4, resource exhaustion can occur because of a lack of a check in BeanDeserializer._deserializeFromArray to prevent use of deeply nested arrays. This issue can only happen when the UNWRAP_SINGLE_VALUE_ARRAYS feature is explicitly enabled.

Severity

7.5 (High)


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

8.2 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.4.0-rc1"
            },
            {
              "fixed": "2.12.7.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-databind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.13.0"
            },
            {
              "fixed": "2.13.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2022-42004"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2022-10-04T21:56:21Z",
    "nvd_published_at": "2022-10-02T05:15:00Z",
    "severity": "HIGH"
  },
  "details": "In FasterXML jackson-databind before 2.12.7.1 and in 2.13.x before 2.13.4, resource exhaustion can occur because of a lack of a check in BeanDeserializer._deserializeFromArray to prevent use of deeply nested arrays. This issue can only happen when the `UNWRAP_SINGLE_VALUE_ARRAYS` feature is explicitly enabled.",
  "id": "GHSA-rgv9-q543-rqg4",
  "modified": "2026-05-21T00:22:42Z",
  "published": "2022-10-03T00:00:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-42004"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/issues/3582"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/063183589218fec19a9293ed2f17ec53ea80ba88"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/0e37a39502439ecbaa1a5b5188387c01bf7f7fa1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/35de19e7144c4df8ab178b800ba86e80c3d84252"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-databind/commit/cd090979b7ea78c75e4de8a4aed04f7e9fa8deea"
    },
    {
      "type": "WEB",
      "url": "https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=50490"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/FasterXML/jackson-databind"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2022/11/msg00035.html"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202210-21"
    },
    {
      "type": "WEB",
      "url": "https://security.netapp.com/advisory/ntap-20221118-0008"
    },
    {
      "type": "WEB",
      "url": "https://www.debian.org/security/2022/dsa-5283"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Uncontrolled Resource Consumption in FasterXML jackson-databind"
}

GHSA-RGVC-FQR7-3HVM

Vulnerability from github – Published: 2026-03-25 18:31 – Updated: 2026-03-26 15:30

Details

Deserialization of Untrusted Data vulnerability in Edge-Themes Gracey gracey allows Object Injection.This issue affects Gracey: from n/a through < 1.4.

Severity

5.4 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-32509"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-25T17:17:03Z",
    "severity": "MODERATE"
  },
  "details": "Deserialization of Untrusted Data vulnerability in Edge-Themes Gracey gracey allows Object Injection.This issue affects Gracey: from n/a through \u003c 1.4.",
  "id": "GHSA-rgvc-fqr7-3hvm",
  "modified": "2026-03-26T15:30:34Z",
  "published": "2026-03-25T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32509"
    },
    {
      "type": "WEB",
      "url": "https://patchstack.com/database/Wordpress/Theme/gracey/vulnerability/wordpress-gracey-theme-1-4-arbitrary-object-instantiation-vulnerability?_s_id=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RH47-6J8G-CR2X

Vulnerability from github – Published: 2023-04-28 00:30 – Updated: 2024-04-04 03:43

Details

Keysight N8844A Data Analytics Web Service deserializes untrusted data without sufficiently verifying the resulting data will be valid.

Severity

9.8 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2023-1967"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-04-27T22:15:09Z",
    "severity": "CRITICAL"
  },
  "details": "Keysight N8844A Data Analytics Web Service deserializes untrusted data without sufficiently verifying the resulting data will be valid. ",
  "id": "GHSA-rh47-6j8g-cr2x",
  "modified": "2024-04-04T03:43:08Z",
  "published": "2023-04-28T00:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1967"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/news-events/ics-advisories/icsa-23-115-01"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RH4J-5RHW-HR54

Vulnerability from github – Published: 2025-01-27 20:50 – Updated: 2025-06-30 12:52

Summary

vllm: Malicious model to RCE by torch.load in hf_model_weights_iterator

Details

Description

The vllm/model_executor/weight_utils.py implements hf_model_weights_iterator to load the model checkpoint, which is downloaded from huggingface. It use torch.load function and weights_only parameter is default value False. There is a security warning on https://pytorch.org/docs/stable/generated/torch.load.html, when torch.load load a malicious pickle data it will execute arbitrary code during unpickling.

Impact

This vulnerability can be exploited to execute arbitrary codes and OS commands in the victim machine who fetch the pretrained repo remotely.

Note that most models now use the safetensors format, which is not vulnerable to this issue.

References

https://pytorch.org/docs/stable/generated/torch.load.html
Fix: https://github.com/vllm-project/vllm/pull/12366

Severity

7.5 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vllm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.7.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-24357"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-01-27T20:50:30Z",
    "nvd_published_at": "2025-01-27T18:15:41Z",
    "severity": "HIGH"
  },
  "details": "### Description\nThe vllm/model_executor/weight_utils.py implements hf_model_weights_iterator to load the model checkpoint, which is downloaded from huggingface. It use torch.load function and weights_only parameter is default value False. There is a security warning on https://pytorch.org/docs/stable/generated/torch.load.html, when torch.load load a malicious pickle data it will execute arbitrary code during unpickling.\n\n### Impact\nThis vulnerability can be exploited to execute arbitrary codes and OS commands in the victim machine who fetch the pretrained repo remotely.\n\nNote that most models now use the safetensors format, which is not vulnerable to this issue.\n\n### References\n* https://pytorch.org/docs/stable/generated/torch.load.html\n* Fix: https://github.com/vllm-project/vllm/pull/12366",
  "id": "GHSA-rh4j-5rhw-hr54",
  "modified": "2025-06-30T12:52:27Z",
  "published": "2025-01-27T20:50:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/security/advisories/GHSA-rh4j-5rhw-hr54"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-24357"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/pull/12366"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/commit/d3d6bb13fb62da3234addf6574922a4ec0513d04"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2025-58.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vllm-project/vllm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/releases/tag/v0.7.0"
    },
    {
      "type": "WEB",
      "url": "https://pytorch.org/docs/stable/generated/torch.load.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "vllm: Malicious model to RCE by torch.load in hf_model_weights_iterator"
}

GHSA-RHP5-R9X4-F5G2

Vulnerability from github – Published: 2026-09-08 16:41 – Updated: 2026-09-08 16:41

Summary

NLTK: Unsafe Pickle Deserialization in TransitionParser Allows Remote Code Execution

Details

Summary

The NLTK library's TransitionParser.parse() method deserializes model files using pickle_load() with the default restricted=False parameter, allowing arbitrary Python code execution when loading a malicious model file. The library provides a RestrictedUnpickler class for safe deserialization, but it is never used by production code paths, leaving the vulnerability unpatched.

Root Cause

File: nltk/parse/transitionparser.py (lines 542-557)

The parse() method calls pickle_load(f) without restricted=True, routing through WarningUnpickler which inherits from pickle.Unpickler and does NOT override find_class(). This allows arbitrary class/function resolution during unpickling, enabling RCE via standard pickle gadgets (e.g., os.system, subprocess.Popen).

Vulnerability chain in nltk/picklesec.py:

def pickle_load(file, *, context=None, restricted=False):
    if restricted:
        return RestrictedUnpickler(file).load()  # Safe: blocks all globals
    return WarningUnpickler(file, context=context).load()  # VULNERABLE PATH

WarningUnpickler only emits a warning but does NOT block unsafe class loading — it calls super().load() which is standard pickle.Unpickler.load().

Why this is not by design: - NLTK intentionally created RestrictedUnpickler to block unsafe deserialization - The restricted=True parameter exists in the API but is never used by any production code path - All call sites use the default restricted=False: transitionparser.py:557, parse/chartparser_app.py:816, parse/chartparser_app.py:2273, parse/chartparser_app.py:2311

Attack Surface

Entry point: TransitionParser().parse(depgraphs, modelFile) receives a filesystem path with no validation.

Exploitation path: 1. Attacker places a malicious pickle file at a known or attacker-controlled location 2. Victim calls parser.parse(sentences, "/path/to/malicious_model.pkl") 3. pickle_load() deserializes the file with restricted=False (default) 4. Standard pickle gadget chain executes arbitrary Python code with victim's privileges

Impact: Remote code execution with the privileges of the user running the NLTK-dependent application. Affects researchers, data scientists, and automated ML pipelines using NLTK for parsing tasks.

Steps to Reproduce

Environment

NLTK version: 3.8.1+ (all versions with transitionparser.py)
Python 3.6+
No special dependencies required

Reproduction

Create a malicious pickle file that uses __reduce__ to execute a system command during deserialization.
Call TransitionParser().parse([], '/path/to/malicious_model.pkl').
The pickle_load(f) call at transitionparser.py:557 uses restricted=False by default, routing through WarningUnpickler, which does not override find_class() and permits full class resolution — executing the embedded gadget.
Arbitrary code executes with the victim's privileges.

Proof That the Fix Works

Changing line 557 in transitionparser.py from:

model = pickle_load(f)

to:

model = pickle_load(f, restricted=True)

causes RestrictedUnpickler to raise an UnpicklingError and block execution, confirming the safe path prevents the attack.

Working PoC

import pickle
import os
from nltk.parse.transitionparser import TransitionParser

# Create malicious pickle with RCE payload
class Exploit:
    def __reduce__(self):
        return (os.system, ('touch /tmp/nltk_poc_triggered',))

with open('/tmp/malicious_model.pkl', 'wb') as f:
    pickle.dump(Exploit(), f)

# Trigger the vulnerable code path (requires algorithm argument in ≤ 3.9.4)
parser = TransitionParser('arc-standard')      # or 'arc-eager'
parser.parse([], '/tmp/malicious_model.pkl')   # loads and unpickles unsafely

# Exploit succeeds: file /tmp/nltk_poc_triggered is created

On NLTK ≥ 3.10.0 (patched), the same code fails with:

_pickle.UnpicklingError: global 'posix.system' is not in the pickle allowlist

This proves the vulnerability exists in versions ≤ 3.9.4 and is fixed in 3.10.0+.

Recommended Fix

Change all call sites to use restricted=True:

File	Line	Before	After
`nltk/parse/transitionparser.py`	557	`pickle_load(f)`	`pickle_load(f, restricted=True)`
`nltk/parse/chartparser_app.py`	816	`pickle_load(model_data_file)`	`pickle_load(model_data_file, restricted=True)`
`nltk/parse/chartparser_app.py`	2273	`pickle_load(file)`	`pickle_load(file, restricted=True)`
`nltk/parse/chartparser_app.py`	2311	`pickle_load(fp)`	`pickle_load(fp, restricted=True)`

Note: This fix may affect loading older sklearn models. A more robust approach would implement a module allowlist in RestrictedUnpickler.find_class().

Severity

9.4 (Critical)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.9.4"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "nltk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-78683"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T16:41:11Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "## Summary\n\nThe NLTK library\u0027s `TransitionParser.parse()` method deserializes model files using `pickle_load()` with the default `restricted=False` parameter, allowing arbitrary Python code execution when loading a malicious model file. The library provides a `RestrictedUnpickler` class for safe deserialization, but it is never used by production code paths, leaving the vulnerability unpatched.\n\n## Root Cause\n\n**File:** `nltk/parse/transitionparser.py` (lines 542-557)\n\nThe `parse()` method calls `pickle_load(f)` without `restricted=True`, routing through `WarningUnpickler` which inherits from `pickle.Unpickler` and does NOT override `find_class()`. This allows arbitrary class/function resolution during unpickling, enabling RCE via standard pickle gadgets (e.g., `os.system`, `subprocess.Popen`).\n\n**Vulnerability chain in `nltk/picklesec.py`:**\n\n```python\ndef pickle_load(file, *, context=None, restricted=False):\n    if restricted:\n        return RestrictedUnpickler(file).load()  # Safe: blocks all globals\n    return WarningUnpickler(file, context=context).load()  # VULNERABLE PATH\n```\n\n`WarningUnpickler` only emits a warning but does NOT block unsafe class loading \u2014 it calls `super().load()` which is standard `pickle.Unpickler.load()`.\n\n**Why this is not by design:**\n- NLTK intentionally created `RestrictedUnpickler` to block unsafe deserialization\n- The `restricted=True` parameter exists in the API but is **never used** by any production code path\n- All call sites use the default `restricted=False`: `transitionparser.py:557`, `parse/chartparser_app.py:816`, `parse/chartparser_app.py:2273`, `parse/chartparser_app.py:2311`\n\n## Attack Surface\n\n**Entry point:** `TransitionParser().parse(depgraphs, modelFile)` receives a filesystem path with no validation.\n\n**Exploitation path:**\n1. Attacker places a malicious pickle file at a known or attacker-controlled location\n2. Victim calls `parser.parse(sentences, \"/path/to/malicious_model.pkl\")`\n3. `pickle_load()` deserializes the file with `restricted=False` (default)\n4. Standard pickle gadget chain executes arbitrary Python code with victim\u0027s privileges\n\n**Impact:** Remote code execution with the privileges of the user running the NLTK-dependent application. Affects researchers, data scientists, and automated ML pipelines using NLTK for parsing tasks.\n\n## Steps to Reproduce\n\n### Environment\n- NLTK version: 3.8.1+ (all versions with `transitionparser.py`)\n- Python 3.6+\n- No special dependencies required\n\n### Reproduction\n\n1. Create a malicious pickle file that uses `__reduce__` to execute a system command during deserialization.\n\n2. Call `TransitionParser().parse([], \u0027/path/to/malicious_model.pkl\u0027)`.\n\n3. The `pickle_load(f)` call at `transitionparser.py:557` uses `restricted=False` by default, routing through `WarningUnpickler`, which does not override `find_class()` and permits full class resolution \u2014 executing the embedded gadget.\n\n4. Arbitrary code executes with the victim\u0027s privileges.\n\n### Proof That the Fix Works\n\nChanging line 557 in `transitionparser.py` from:\n```python\nmodel = pickle_load(f)\n```\nto:\n```python\nmodel = pickle_load(f, restricted=True)\n```\ncauses `RestrictedUnpickler` to raise an `UnpicklingError` and block execution, confirming the safe path prevents the attack.\n\n### Working PoC\n\n```python\nimport pickle\nimport os\nfrom nltk.parse.transitionparser import TransitionParser\n\n# Create malicious pickle with RCE payload\nclass Exploit:\n    def __reduce__(self):\n        return (os.system, (\u0027touch /tmp/nltk_poc_triggered\u0027,))\n\nwith open(\u0027/tmp/malicious_model.pkl\u0027, \u0027wb\u0027) as f:\n    pickle.dump(Exploit(), f)\n\n# Trigger the vulnerable code path (requires algorithm argument in \u2264 3.9.4)\nparser = TransitionParser(\u0027arc-standard\u0027)      # or \u0027arc-eager\u0027\nparser.parse([], \u0027/tmp/malicious_model.pkl\u0027)   # loads and unpickles unsafely\n\n# Exploit succeeds: file /tmp/nltk_poc_triggered is created\n```\n\nOn NLTK \u2265 3.10.0 (patched), the same code fails with:\n\n```\n_pickle.UnpicklingError: global \u0027posix.system\u0027 is not in the pickle allowlist\n```\n\nThis proves the vulnerability exists in versions \u2264 3.9.4 and is fixed in 3.10.0+.\n\n## Recommended Fix\n\nChange all call sites to use `restricted=True`:\n\n| File | Line | Before | After |\n|------|------|--------|-------|\n| `nltk/parse/transitionparser.py` | 557 | `pickle_load(f)` | `pickle_load(f, restricted=True)` |\n| `nltk/parse/chartparser_app.py` | 816 | `pickle_load(model_data_file)` | `pickle_load(model_data_file, restricted=True)` |\n| `nltk/parse/chartparser_app.py` | 2273 | `pickle_load(file)` | `pickle_load(file, restricted=True)` |\n| `nltk/parse/chartparser_app.py` | 2311 | `pickle_load(fp)` | `pickle_load(fp, restricted=True)` |\n\n**Note:** This fix may affect loading older sklearn models. A more robust approach would implement a module allowlist in `RestrictedUnpickler.find_class()`.",
  "id": "GHSA-rhp5-r9x4-f5g2",
  "modified": "2026-09-08T16:41:11Z",
  "published": "2026-09-08T16:41:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/security/advisories/GHSA-rhp5-r9x4-f5g2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78683"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/pull/3631"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/f26b3753038d937b68145daf15e9636f8451053c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nltk/nltk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/releases/tag/v3.10.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3734.yaml"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nltk-before-remote-code-execution-via-unsafe-pickle-deserialization"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "NLTK: Unsafe Pickle Deserialization in TransitionParser Allows Remote Code Execution"
}

Mitigation

Architecture and Design Implementation

If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.

Mitigation

Implementation

When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.

Mitigation

Implementation

Explicitly define a final object() to prevent deserialization.

Mitigation

Architecture and Design Implementation

Make fields transient to protect them from deserialization.
An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

Mitigation

Implementation

Avoid having unnecessary types or gadgets (a sequence of instances and method invocations that can self-execute during the deserialization process, often found in libraries) available that can be leveraged for malicious ends. This limits the potential for unintended or unauthorized types and gadgets to be leveraged by the attacker. Add only acceptable classes to an allowlist. Note: new gadgets are constantly being discovered, so this alone is not a sufficient mitigation.

Mitigation

Architecture and Design Implementation

Employ cryptography of the data or code for protection. However, it's important to note that it would still be client-side security. This is risky because if the client is compromised then the security implemented on the client (the cryptography) can be bypassed.

Mitigation MIT-29

Operation

Strategy: Firewall

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].

CAPEC-586: Object Injection

An adversary attempts to exploit an application by injecting additional, malicious content during its processing of serialized objects. Developers leverage serialization in order to convert data or state into a static, binary format for saving to disk or transferring over a network. These objects are then deserialized when needed to recover the data/state. By injecting a malformed object into a vulnerable application, an adversary can potentially compromise the application by manipulating the deserialization process. This can result in a number of unwanted outcomes, including remote code execution.

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