Common Weakness Enumeration

CWE-434

Allowed

Unrestricted Upload of File with Dangerous Type

Abstraction: Base · Status: Draft

The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

6195 vulnerabilities reference this CWE, most recent first.

GHSA-XP53-G87W-P23F

Vulnerability from github – Published: 2026-07-10 06:31 – Updated: 2026-07-10 06:31
VLAI
Details

The Instant Appointment plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'insapp_upload_image_as_attachment' function in all versions up to, and including, 1.2. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-15282"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-10T05:16:30Z",
    "severity": "CRITICAL"
  },
  "details": "The Instant Appointment plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the \u0027insapp_upload_image_as_attachment\u0027 function in all versions up to, and including, 1.2. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site\u0027s server which may make remote code execution possible.",
  "id": "GHSA-xp53-g87w-p23f",
  "modified": "2026-07-10T06:31:20Z",
  "published": "2026-07-10T06:31:20Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15282"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/instant-appointment/trunk/includes/ajax/ajax_services.php#L3"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/instant-appointment/trunk/includes/front-end/ajax/login_ajax.php#L584"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/instant-appointment/trunk/includes/front-end/ajax/login_ajax.php#L598"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/097b1530-64fa-45b2-85f3-c6a2311405b5?source=cve"
    }
  ],
  "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-XP5R-PHW6-JCR2

Vulnerability from github – Published: 2026-08-26 18:31 – Updated: 2026-08-26 18:31
VLAI
Details

The ERP: Complete HR, Accounting & CRM Suite Built for WooCommerce plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 1.17.8 via the save_attachments() function. This is due to missing file extension validation and missing path normalization when CRM Email Connect processes inbound IMAP email attachments. This makes it possible for unauthenticated attackers to send a crafted email to the site's configured inbound mailbox with a forged References header matching the plugin's expected pattern and an attachment filename such as ../helper.php, causing the cron-based IMAP sync job to write attacker-controlled PHP outside of the .htaccess-protected crm-attachments directory and into wp-content/uploads/. On configurations where PHP executes in uploads, this can lead to remote code execution. Exploitation requires the CRM module and IMAP Email Connect feature to be enabled and configured.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-18080"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T11:16:37Z",
    "severity": "CRITICAL"
  },
  "details": "The ERP: Complete HR, Accounting \u0026 CRM Suite Built for WooCommerce plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 1.17.8 via the save_attachments() function. This is due to missing file extension validation and missing path normalization when CRM Email Connect processes inbound IMAP email attachments. This makes it possible for unauthenticated attackers to send a crafted email to the site\u0027s configured inbound mailbox with a forged References header matching the plugin\u0027s expected pattern and an attachment filename such as `../helper.php`, causing the cron-based IMAP sync job to write attacker-controlled PHP outside of the .htaccess-protected `crm-attachments` directory and into `wp-content/uploads/`. On configurations where PHP executes in uploads, this can lead to remote code execution. Exploitation requires the CRM module and IMAP Email Connect feature to be enabled and configured.",
  "id": "GHSA-xp5r-phw6-jcr2",
  "modified": "2026-08-26T18:31:54Z",
  "published": "2026-08-26T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18080"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/changeset/3656848/erp"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/b9d11eb9-5e18-459f-a9d4-cccb1d593402?source=cve"
    }
  ],
  "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-XP68-7G33-F49M

Vulnerability from github – Published: 2024-08-29 15:30 – Updated: 2024-08-30 19:53
VLAI
Summary
FeehiCMS User[avatar] unrestricted upload
Details

A vulnerability was found in FeehiCMS up to 2.1.1 and classified as critical. This issue affects the function insert of the file /admin/index.php?r=user%2Fcreate. The manipulation of the argument User[avatar] leads to unrestricted upload. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "feehi/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-8296"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-08-30T19:53:34Z",
    "nvd_published_at": "2024-08-29T13:15:07Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability was found in FeehiCMS up to 2.1.1 and classified as critical. This issue affects the function insert of the file /admin/index.php?r=user%2Fcreate. The manipulation of the argument User[avatar] leads to unrestricted upload. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.",
  "id": "GHSA-xp68-7g33-f49m",
  "modified": "2024-08-30T19:53:34Z",
  "published": "2024-08-29T15:30:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-8296"
    },
    {
      "type": "WEB",
      "url": "https://gitee.com/A0kooo/cve_article/blob/master/feehi_cms/file_upload3/Fichkems%20user%20file%20upload%20vulnerability.md"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/liufee/cms"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?ctiid.276071"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?id.276071"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?submit.394568"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/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"
    }
  ],
  "summary": "FeehiCMS User[avatar]  unrestricted upload"
}

GHSA-XP82-JMW8-MJXP

Vulnerability from github – Published: 2022-03-23 00:00 – Updated: 2022-03-30 19:58
VLAI
Summary
Unrestricted Upload of File with Dangerous Type in ShowDoc
Details

There is a Unrestricted Upload of File vulnerability in ShowDoc prior to version 2.10.4.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "showdoc/showdoc"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.10.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2022-1034"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2022-03-30T19:58:48Z",
    "nvd_published_at": "2022-03-22T08:15:00Z",
    "severity": "HIGH"
  },
  "details": "There is a Unrestricted Upload of File vulnerability in ShowDoc prior to version 2.10.4.",
  "id": "GHSA-xp82-jmw8-mjxp",
  "modified": "2022-03-30T19:58:48Z",
  "published": "2022-03-23T00:00:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-1034"
    },
    {
      "type": "WEB",
      "url": "https://github.com/star7th/showdoc/commit/bd792a89c0325836fbd64784f4c4117c0171416b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/star7th/showdoc"
    },
    {
      "type": "WEB",
      "url": "https://huntr.dev/bounties/d205c489-3266-4ac4-acb7-c8ee570887f7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Unrestricted Upload of File with Dangerous Type in ShowDoc"
}

GHSA-XP8C-VFH9-64V5

Vulnerability from github – Published: 2023-10-03 12:30 – Updated: 2024-04-04 08:06
VLAI
Details

There is a remote code execution vulnerability that affects all versions of NetMan 204. A remote attacker could upload a firmware file containing a webshell, that could allow him to execute arbitrary code as root.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2022-47893"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-10-03T12:15:10Z",
    "severity": "CRITICAL"
  },
  "details": "There is a remote code execution vulnerability that affects all versions of NetMan 204. A remote attacker could upload a firmware file containing a webshell, that could allow him to execute arbitrary code as root.",
  "id": "GHSA-xp8c-vfh9-64v5",
  "modified": "2024-04-04T08:06:48Z",
  "published": "2023-10-03T12:30:20Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-47893"
    },
    {
      "type": "WEB",
      "url": "https://www.incibe.es/incibe-cert/alerta-temprana/avisos-sci/multiples-vulnerabilidades-netman-204-riello-ups"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-XP9H-33F6-625F

Vulnerability from github – Published: 2022-05-24 19:16 – Updated: 2022-05-24 19:16
VLAI
Details

Zoho ManageEngine ADManager Plus version 7110 and prior allows unrestricted file upload which leads to remote code execution.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2021-37920"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-10-07T16:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "Zoho ManageEngine ADManager Plus version 7110 and prior allows unrestricted file upload which leads to remote code execution.",
  "id": "GHSA-xp9h-33f6-625f",
  "modified": "2022-05-24T19:16:56Z",
  "published": "2022-05-24T19:16:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-37920"
    },
    {
      "type": "WEB",
      "url": "https://www.manageengine.com"
    },
    {
      "type": "WEB",
      "url": "https://www.manageengine.com/products/ad-manager/release-notes.html#7111"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-XPPH-PF69-7F23

Vulnerability from github – Published: 2023-10-03 21:30 – Updated: 2024-04-04 08:13
VLAI
Details

An arbitrary file upload vulnerability in the component /admin/plugin.php of Emlog Pro v2.2.0 allows attackers to execute arbitrary code via uploading a crafted PHP file.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-44974"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-10-03T21:15:10Z",
    "severity": "CRITICAL"
  },
  "details": "An arbitrary file upload vulnerability in the component /admin/plugin.php of Emlog Pro v2.2.0 allows attackers to execute arbitrary code via uploading a crafted PHP file.",
  "id": "GHSA-xpph-pf69-7f23",
  "modified": "2024-04-04T08:13:10Z",
  "published": "2023-10-03T21:30:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-44974"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yangliukk/emlog/blob/main/Plugin-getshell.md"
    }
  ],
  "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-XPXJ-GV5M-476X

Vulnerability from github – Published: 2026-06-17 18:35 – Updated: 2026-06-17 18:35
VLAI
Details

Subscriber Arbitrary File Upload in Grip <= 1.0.9 versions.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-52488"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-17T13:19:12Z",
    "severity": "CRITICAL"
  },
  "details": "Subscriber Arbitrary File Upload in Grip \u003c= 1.0.9 versions.",
  "id": "GHSA-xpxj-gv5m-476x",
  "modified": "2026-06-17T18:35:42Z",
  "published": "2026-06-17T18:35:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-52488"
    },
    {
      "type": "WEB",
      "url": "https://patchstack.com/database/wordpress/theme/grip/vulnerability/wordpress-grip-theme-1-0-9-arbitrary-plugin-activation-deactivation-to-rce-vulnerability?_s_id=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-XQ28-W75V-29RR

Vulnerability from github – Published: 2022-05-24 17:18 – Updated: 2026-08-19 18:31
VLAI
Details

A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package, aka 'Microsoft SharePoint Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2020-1023, CVE-2020-1024.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2020-1102"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2020-05-21T23:15:00Z",
    "severity": "MODERATE"
  },
  "details": "A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package, aka \u0027Microsoft SharePoint Remote Code Execution Vulnerability\u0027. This CVE ID is unique from CVE-2020-1023, CVE-2020-1024.",
  "id": "GHSA-xq28-w75v-29rr",
  "modified": "2026-08-19T18:31:20Z",
  "published": "2022-05-24T17:18:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-1102"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-1102"
    },
    {
      "type": "WEB",
      "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1102"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-XQ2V-8QF4-3RG6

Vulnerability from github – Published: 2026-07-11 06:31 – Updated: 2026-07-11 06:31
VLAI
Details

The Swiss Toolkit For WP plugin for WordPress is vulnerable to arbitrary file upload due to a flawed file type validation bypass in the upload_extension_files() function in all versions up to, and including, 1.4.6. The upload_extension_files() function hooks into WordPress's wp_check_filetype_and_ext filter and uses strpos() to check if a filename contains a configured extension string, rather than verifying the actual file extension. This makes it possible for authenticated attackers, with Author-level access and above, to upload arbitrary files (including PHP) on the affected site's server which may make remote code execution possible, granted the "Enhanced Multi-Format Image Support" feature is enabled with at least one extension (e.g., avif) in the allowed formats.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-2354"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-11T05:16:33Z",
    "severity": "HIGH"
  },
  "details": "The Swiss Toolkit For WP plugin for WordPress is vulnerable to arbitrary file upload due to a flawed file type validation bypass in the `upload_extension_files()` function in all versions up to, and including, 1.4.6. The `upload_extension_files()` function hooks into WordPress\u0027s `wp_check_filetype_and_ext` filter and uses `strpos()` to check if a filename contains a configured extension string, rather than verifying the actual file extension. This makes it possible for authenticated attackers, with Author-level access and above, to upload arbitrary files (including PHP) on the affected site\u0027s server which may make remote code execution possible, granted the \"Enhanced Multi-Format Image Support\" feature is enabled with at least one extension (e.g., avif) in the allowed formats.",
  "id": "GHSA-xq2v-8qf4-3rg6",
  "modified": "2026-07-11T06:31:16Z",
  "published": "2026-07-11T06:31:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-2354"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/swiss-toolkit-for-wp/tags/1.4.2/includes/plugins/class-boomdevs-swiss-toolkit-extension-supports.php#L49"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/swiss-toolkit-for-wp/tags/1.4.2/includes/plugins/class-boomdevs-swiss-toolkit-extension-supports.php#L95"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/swiss-toolkit-for-wp/trunk/includes/plugins/class-boomdevs-swiss-toolkit-extension-supports.php#L49"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/swiss-toolkit-for-wp/trunk/includes/plugins/class-boomdevs-swiss-toolkit-extension-supports.php#L95"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/06bccd2e-6891-433a-9f5b-3ec0c30afef4?source=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Mitigation
Architecture and Design

Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.[REF-422] [REF-423]

Mitigation MIT-21
Architecture and Design

Strategy: Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

Mitigation
Architecture and Design

Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically. [REF-423]

Mitigation MIT-5
Implementation

Strategy: Input Validation

  • Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • For example, limiting filenames to alphanumeric characters can help to restrict the introduction of unintended file extensions.
Mitigation
Architecture and Design

Define a very limited set of allowable extensions and only generate filenames that end in these extensions. Consider the possibility of XSS (CWE-79) before allowing .html or .htm file types.

Mitigation
Implementation

Strategy: Input Validation

Ensure that only one extension is used in the filename. Some web servers, including some versions of Apache, may process files based on inner extensions so that "filename.php.gif" is fed to the PHP interpreter.[REF-422] [REF-423]

Mitigation
Implementation

When running on a web server that supports case-insensitive filenames, perform case-insensitive evaluations of the extensions that are provided.

Mitigation MIT-15
Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Mitigation
Implementation

Do not rely exclusively on sanity checks of file contents to ensure that the file is of the expected type and size. It may be possible for an attacker to hide code in some file segments that will still be executed by the server. For example, GIF images may contain a free-form comments field.

Mitigation
Implementation

Do not rely exclusively on the MIME content type or filename attribute when determining how to render a file. Validating the MIME content type and ensuring that it matches the extension is only a partial solution.

Mitigation MIT-17
Architecture and Design Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Mitigation MIT-22
Architecture and Design Operation

Strategy: Sandbox or Jail

  • Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
  • OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
  • This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
  • Be careful to avoid CWE-243 and other weaknesses related to jails.
CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs

In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.