Common Weakness Enumeration

CWE-22

Allowed-with-Review

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Abstraction: Base · Status: Stable

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

13273 vulnerabilities reference this CWE, most recent first.

GHSA-MMHX-6X77-4JF4

Vulnerability from github – Published: 2022-07-12 00:00 – Updated: 2022-07-16 00:00
VLAI
Details

The Delor4/CarceresBE repository through 1.0 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2022-31515"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-07-11T01:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "The Delor4/CarceresBE repository through 1.0 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.",
  "id": "GHSA-mmhx-6x77-4jf4",
  "modified": "2022-07-16T00:00:32Z",
  "published": "2022-07-12T00:00:57Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-31515"
    },
    {
      "type": "WEB",
      "url": "https://github.com/github/securitylab/issues/669#issuecomment-1117265726"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-MMJ6-R83C-HQ4F

Vulnerability from github – Published: 2023-06-27 00:30 – Updated: 2024-04-04 05:11
VLAI
Details

A path traversal vulnerability in the Trend Micro Apex One and Apex One as a Service could allow an unauthenticated attacker to upload an arbitrary file to the Management Server which could lead to remote code execution with system privileges.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-32557"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-06-26T22:15:10Z",
    "severity": "CRITICAL"
  },
  "details": "A path traversal vulnerability in the Trend Micro Apex One and Apex One as a Service could allow an unauthenticated attacker to upload an arbitrary file to the Management Server which could lead to remote code execution with system privileges.",
  "id": "GHSA-mmj6-r83c-hq4f",
  "modified": "2024-04-04T05:11:29Z",
  "published": "2023-06-27T00:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-32557"
    },
    {
      "type": "WEB",
      "url": "https://success.trendmicro.com/dcx/s/solution/000293108?language=en_US"
    }
  ],
  "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-MMMG-93RW-WXJF

Vulnerability from github – Published: 2026-02-03 18:30 – Updated: 2026-02-04 18:30
VLAI
Details

Articentgroup Zip Rar Extractor Tool 1.345.93.0 is vulnerable to Directory Traversal. The vulnerability resides in the ZIP file processing component, specifically in the functionality responsible for extracting and handling ZIP archive contents.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-63372"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-03T18:16:15Z",
    "severity": "HIGH"
  },
  "details": "Articentgroup Zip Rar Extractor Tool 1.345.93.0 is vulnerable to Directory Traversal. The vulnerability resides in the ZIP file processing component, specifically in the functionality responsible for extracting and handling ZIP archive contents.",
  "id": "GHSA-mmmg-93rw-wxjf",
  "modified": "2026-02-04T18:30:30Z",
  "published": "2026-02-03T18:30:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-63372"
    },
    {
      "type": "WEB",
      "url": "https://articentgroup.com/zip-rar-extractor-tool"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-MMPF-X6C4-5PVR

Vulnerability from github – Published: 2022-05-24 16:46 – Updated: 2024-04-04 00:45
VLAI
Details

Adobe XD versions 16.0 and earlier have a path traversal vulnerability. Successful exploitation could lead to arbitrary code execution.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2019-7106"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2019-05-23T16:29:00Z",
    "severity": "CRITICAL"
  },
  "details": "Adobe XD versions 16.0 and earlier have a path traversal vulnerability. Successful exploitation could lead to arbitrary code execution.",
  "id": "GHSA-mmpf-x6c4-5pvr",
  "modified": "2024-04-04T00:45:51Z",
  "published": "2022-05-24T16:46:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-7106"
    },
    {
      "type": "WEB",
      "url": "https://helpx.adobe.com/security/products/xd/apsb19-22.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-MMQW-M38J-RFMQ

Vulnerability from github – Published: 2022-05-17 05:32 – Updated: 2022-05-17 05:32
VLAI
Details

Directory traversal vulnerability in the WWWHELP Service (js/html/wwhelp.htm) in Cyberoam Central Console (CCC) 2.00.2 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the file parameter in an Online_help action.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2012-1047"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2012-02-12T22:55:00Z",
    "severity": "HIGH"
  },
  "details": "Directory traversal vulnerability in the WWWHELP Service (js/html/wwhelp.htm) in Cyberoam Central Console (CCC) 2.00.2 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the file parameter in an Online_help action.",
  "id": "GHSA-mmqw-m38j-rfmq",
  "modified": "2022-05-17T05:32:58Z",
  "published": "2022-05-17T05:32:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2012-1047"
    },
    {
      "type": "WEB",
      "url": "http://archives.neohapsis.com/archives/bugtraq/2012-02/0036.html"
    },
    {
      "type": "WEB",
      "url": "http://www.exploit-db.com/exploits/18473"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/51901"
    },
    {
      "type": "WEB",
      "url": "http://www.vulnerability-lab.com/get_content.php?id=405"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-MMWP-46JQ-RWV5

Vulnerability from github – Published: 2025-07-14 18:30 – Updated: 2025-07-14 18:30
VLAI
Details

A vulnerability, which was classified as critical, was found in YiJiuSmile kkFileViewOfficeEdit up to 5fbc57c48e8fe6c1b91e0e7995e2d59615f37abd. Affected is the function Download of the file /download. The manipulation of the argument url leads to path traversal. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. Continious delivery with rolling releases is used by this product. Therefore, no version details of affected nor updated releases are available.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2025-7625"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-14T17:15:39Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability, which was classified as critical, was found in YiJiuSmile kkFileViewOfficeEdit up to 5fbc57c48e8fe6c1b91e0e7995e2d59615f37abd. Affected is the function Download of the file /download. The manipulation of the argument url leads to path traversal. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. Continious delivery with rolling releases is used by this product. Therefore, no version details of affected nor updated releases are available.",
  "id": "GHSA-mmwp-46jq-rwv5",
  "modified": "2025-07-14T18:30:43Z",
  "published": "2025-07-14T18:30:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-7625"
    },
    {
      "type": "WEB",
      "url": "https://github.com/YiJiuSmile/kkFileViewOfficeEdit/issues/12"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?ctiid.316326"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?id.316326"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/?submit.609076"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/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-MMWX-79F6-67JG

Vulnerability from github – Published: 2026-01-16 16:58 – Updated: 2026-01-16 21:56
VLAI
Summary
Weblate wlc path traversal vulnerability: Unsanitized API slugs in download command
Details

Impact

Multi-translation download could write to an arbitrary location when instructed by a crafted server.

Patches

  • https://github.com/WeblateOrg/wlc/pull/1128

Workarounds

Do not use wlc download with untrusted servers.

References

This issue was reported to us by wh1zee via HackerOne.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "wlc"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.17.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-23535"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-16T16:58:26Z",
    "nvd_published_at": "2026-01-16T19:16:19Z",
    "severity": "HIGH"
  },
  "details": "### Impact\nMulti-translation download could write to an arbitrary location when instructed by a crafted server.\n\n### Patches\n* https://github.com/WeblateOrg/wlc/pull/1128\n\n### Workarounds\nDo not use `wlc download` with untrusted servers.\n\n### References\nThis issue was reported to us by [wh1zee](https://hackerone.com/wh1zee) via HackerOne.",
  "id": "GHSA-mmwx-79f6-67jg",
  "modified": "2026-01-16T21:56:08Z",
  "published": "2026-01-16T16:58:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/WeblateOrg/wlc/security/advisories/GHSA-mmwx-79f6-67jg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23535"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WeblateOrg/wlc/pull/1128"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WeblateOrg/wlc/commit/216e691c6e50abae97fe2e4e4f21501bf49a585f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/WeblateOrg/wlc"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WeblateOrg/wlc/releases/tag/1.17.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Weblate wlc path traversal vulnerability: Unsanitized API slugs in download command "
}

GHSA-MP2F-45PM-3CG9

Vulnerability from github – Published: 2026-07-06 20:27 – Updated: 2026-07-06 20:27
VLAI
Summary
Decompress: Archive extraction can create files and links outside of the target directory
Details

Impact

When extracting an archive to a directory, a crafted archive can read or write files outside that directory. The flaw is in the code that writes the parsed entries, so it affects every format decompress handles: tar, tar.gz, tar.bz2, and zip by default, plus any others added through the plugins option.

A link (hardlink) or symlink entry is created without checking where its target points. A hardlink can be aimed at any file the running process can read; that file then appears inside the output directory and its contents are exposed. A symlink can point outside the output directory and redirect a later write.

The path containment check used a string prefix comparison (realPath.indexOf(outputPath) !== 0). Output /srv/out does not contain /srv/out-old, but the prefix comparison treats it as inside, so an entry can escape into a sibling directory whose name starts with the output directory name.

File modes were applied as mode & ~umask, which does not remove the setuid, setgid, or sticky bits. A crafted entry can create a setuid or setgid file. This matters when extraction runs as root, for example in CI, containers, or install scripts.

Any code that extracts archives from an untrusted or attacker-influenced source is affected. Archives are commonly downloaded before extraction, so this is reachable over the network in many setups.

Patches

Fixed in @xhmikosr/decompress 10.2.1 and 11.1.3. Link targets are now resolved and checked against the output directory, containment uses path.relative, and setuid, setgid, and sticky bits are removed.

The upstream decompress package is unmaintained, and all versions through its last release (4.2.1) have the same flaws. There is no upstream fix. Migrate to @xhmikosr/decompress 11.1.3 or later.

Workarounds

Extract only archives you trust. Run extraction as a non-root user so the mode issue cannot create a privileged file. After extracting, reject any symlink or hardlink that points outside the target and any file with unexpected mode bits.

Resources

  • Related prior issue in the upstream project this package forks: CVE-2020-12265 / GHSA-qgfr-5hqp-vrw9
  • Fix commits and releases:
  • https://github.com/XhmikosR/decompress/releases/tag/v10.2.1
  • https://github.com/XhmikosR/decompress/releases/tag/v11.1.3
  • https://github.com/XhmikosR/decompress/commit/aca5aac
  • https://github.com/XhmikosR/decompress/commit/281cefa
  • https://github.com/XhmikosR/decompress/commit/60b5299
Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@xhmikosr/decompress"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "10.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "@xhmikosr/decompress"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.0.0"
            },
            {
              "fixed": "11.1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "decompress"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "4.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-53486"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-59",
      "CWE-732"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-06T20:27:38Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nWhen extracting an archive to a directory, a crafted archive can read or write files outside that directory. The flaw is in the code that writes the parsed entries, so it affects every format decompress handles: tar, tar.gz, tar.bz2, and zip by default, plus any others added through the plugins option.\n\nA link (hardlink) or symlink entry is created without checking where its target points. A hardlink can be aimed at any file the running process can read; that file then appears inside the output directory and its contents are exposed. A symlink can point outside the output directory and redirect a later write.\n\nThe path containment check used a string prefix comparison (`realPath.indexOf(outputPath) !== 0`). Output `/srv/out` does not contain `/srv/out-old`, but the prefix comparison treats it as inside, so an entry can escape into a sibling directory whose name starts with the output directory name.\n\nFile modes were applied as `mode \u0026 ~umask`, which does not remove the setuid, setgid, or sticky bits. A crafted entry can create a setuid or setgid file. This matters when extraction runs as root, for example in CI, containers, or install scripts.\n\nAny code that extracts archives from an untrusted or attacker-influenced source is affected. Archives are commonly downloaded before extraction, so this is reachable over the network in many setups.\n\n### Patches\n\nFixed in `@xhmikosr/decompress` 10.2.1 and 11.1.3. Link targets are now resolved and checked against the output directory, containment uses `path.relative`, and setuid, setgid, and sticky bits are removed.\n\nThe upstream `decompress` package is unmaintained, and all versions through its last release (4.2.1) have the same flaws. There is no upstream fix. Migrate to `@xhmikosr/decompress` 11.1.3 or later.\n\n### Workarounds\n\nExtract only archives you trust. Run extraction as a non-root user so the mode issue cannot create a privileged file. After extracting, reject any symlink or hardlink that points outside the target and any file with unexpected mode bits.\n\n### Resources\n\n* Related prior issue in the upstream project this package forks: CVE-2020-12265 / GHSA-qgfr-5hqp-vrw9\n* Fix commits and releases:\n  * https://github.com/XhmikosR/decompress/releases/tag/v10.2.1\n  * https://github.com/XhmikosR/decompress/releases/tag/v11.1.3\n  * https://github.com/XhmikosR/decompress/commit/aca5aac\n  * https://github.com/XhmikosR/decompress/commit/281cefa\n  * https://github.com/XhmikosR/decompress/commit/60b5299",
  "id": "GHSA-mp2f-45pm-3cg9",
  "modified": "2026-07-06T20:27:38Z",
  "published": "2026-07-06T20:27:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/XhmikosR/decompress/security/advisories/GHSA-mp2f-45pm-3cg9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/XhmikosR/decompress/commit/281cefa"
    },
    {
      "type": "WEB",
      "url": "https://github.com/XhmikosR/decompress/commit/60b5299"
    },
    {
      "type": "WEB",
      "url": "https://github.com/XhmikosR/decompress/commit/aca5aac"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/XhmikosR/decompress"
    }
  ],
  "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:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Decompress: Archive extraction can create files and links outside of the target directory"
}

GHSA-MP2J-278W-PV83

Vulnerability from github – Published: 2024-09-04 03:30 – Updated: 2024-09-04 03:30
VLAI
Details

Directory traversal vulnerability in the cust module Impact: Successful exploitation of this vulnerability will affect availability and confidentiality.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-45443"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-09-04T03:15:03Z",
    "severity": "MODERATE"
  },
  "details": "Directory traversal vulnerability in the cust module\nImpact: Successful exploitation of this vulnerability will affect availability and confidentiality.",
  "id": "GHSA-mp2j-278w-pv83",
  "modified": "2024-09-04T03:30:45Z",
  "published": "2024-09-04T03:30:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-45443"
    },
    {
      "type": "WEB",
      "url": "https://consumer.huawei.com/en/support/bulletin/2024/9"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-MP6C-G5WV-H2CV

Vulnerability from github – Published: 2022-05-24 16:55 – Updated: 2024-04-04 01:54
VLAI
Details

An issue was discovered in OKLite v1.2.25. framework/admin/tpl_control.php allows remote attackers to delete arbitrary files via a title directory-traversal pathname followed by a crafted substring.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2019-16132"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2019-09-09T03:15:00Z",
    "severity": "MODERATE"
  },
  "details": "An issue was discovered in OKLite v1.2.25. framework/admin/tpl_control.php allows remote attackers to delete arbitrary files via a title directory-traversal pathname followed by a crafted substring.",
  "id": "GHSA-mp6c-g5wv-h2cv",
  "modified": "2024-04-04T01:54:07Z",
  "published": "2022-05-24T16:55:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-16132"
    },
    {
      "type": "WEB",
      "url": "http://www.iwantacve.cn/index.php/archives/296"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

Mitigation MIT-5.1
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.
  • When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
  • Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
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 MIT-20.1
Implementation

Strategy: Input Validation

  • Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
  • Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
  • realpath() in C
  • getCanonicalPath() in Java
  • GetFullPath() in ASP.NET
  • realpath() or abs_path() in Perl
  • realpath() in PHP
Mitigation MIT-4
Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].

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].

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-21.1
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.
  • For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
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.
Mitigation MIT-34
Architecture and Design Operation

Strategy: Attack Surface Reduction

  • Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
  • This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
Implementation
  • Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
  • If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
  • Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
  • In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Operation Implementation

Strategy: Environment Hardening

When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

CAPEC-126: Path Traversal

An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.

CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic

This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.

CAPEC-76: Manipulating Web Input to File System Calls

An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

CAPEC-78: Using Escaped Slashes in Alternate Encoding

This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.

CAPEC-79: Using Slashes in Alternate Encoding

This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.