GHSA-9F46-5R25-5WFM

Vulnerability from github – Published: 2021-06-29 03:13 – Updated: 2021-09-21 14:55
VLAI?
Summary
Time-of-check Time-of-use (TOCTOU) Race Condition in league/flysystem
Details

Impact

The whitespace normalisation using in 1.x and 2.x removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely.

The conditions:

  • A user is allowed to supply the path or filename of an uploaded file.
  • The supplied path or filename is not checked against unicode chars.
  • The supplied pathname checked against an extension deny-list, not an allow-list.
  • The supplied path or filename contains a unicode whitespace char in the extension.
  • The uploaded file is stored in a directory that allows PHP code to be executed.

Given these conditions are met a user can upload and execute arbitrary code on the system under attack.

Patches

The unicode whitespace removal has been replaced with a rejection (exception).

The library has been patched in: - 1.x: https://github.com/thephpleague/flysystem/commit/f3ad69181b8afed2c9edf7be5a2918144ff4ea32 - 2.x: https://github.com/thephpleague/flysystem/commit/a3c694de9f7e844b76f9d1b61296ebf6e8d89d74

Workarounds

For 1.x users, upgrade to 1.1.4. For 2.x users, upgrade to 2.1.1.

Severity ?
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "league/flysystem"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "league/flysystem"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "2.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-32708"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-06-24T18:03:15Z",
    "nvd_published_at": "2021-06-24T17:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nThe whitespace normalisation using in 1.x and 2.x removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely.\n\nThe conditions: \n\n- A user is allowed to supply the path or filename of an uploaded file.\n- The supplied path or filename is not checked against unicode chars.\n- The supplied pathname checked against an extension deny-list, not an allow-list.\n- The supplied path or filename contains a unicode whitespace char in the extension.\n- The uploaded file is stored in a directory that allows PHP code to be executed.\n\nGiven these conditions are met a user can upload and execute arbitrary code on the system under attack.\n\n### Patches\n\nThe unicode whitespace removal has been replaced with a rejection (exception).\n\nThe library has been patched in:\n- 1.x: https://github.com/thephpleague/flysystem/commit/f3ad69181b8afed2c9edf7be5a2918144ff4ea32\n- 2.x: https://github.com/thephpleague/flysystem/commit/a3c694de9f7e844b76f9d1b61296ebf6e8d89d74\n\n### Workarounds\n\nFor 1.x users, upgrade to 1.1.4. For 2.x users, upgrade to 2.1.1.\n",
  "id": "GHSA-9f46-5r25-5wfm",
  "modified": "2021-09-21T14:55:38Z",
  "published": "2021-06-29T03:13:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/thephpleague/flysystem/security/advisories/GHSA-9f46-5r25-5wfm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-32708"
    },
    {
      "type": "WEB",
      "url": "https://github.com/thephpleague/flysystem/commit/a3c694de9f7e844b76f9d1b61296ebf6e8d89d74"
    },
    {
      "type": "WEB",
      "url": "https://github.com/thephpleague/flysystem/commit/f3ad69181b8afed2c9edf7be5a2918144ff4ea32"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/league/flysystem/CVE-2021-32708.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/thephpleague/flysystem"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NWPTENBYKI2IG47GI4DHAACLNRLTWUR5"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RNZSWK4GOMJOOHKLZEOE5AQSLC4DNCRZ"
    },
    {
      "type": "WEB",
      "url": "https://packagist.org/packages/league/flysystem"
    }
  ],
  "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": "Time-of-check Time-of-use (TOCTOU) Race Condition in league/flysystem"
}


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



Detection rules are retrieved from Rulezet.