GHSA-WP53-J4WJ-2CFG

Vulnerability from github – Published: 2026-01-26 23:28 – Updated: 2026-01-29 03:24
VLAI
Summary
Python-Multipart has Arbitrary File Write via Non-Default Configuration
Details

Summary

A Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename.

Details

When UPLOAD_DIR is set and UPLOAD_KEEP_FILENAME is True, the library constructs the file path using os.path.join(file_dir, fname). Due to the behavior of os.path.join(), if the filename begins with a /, all preceding path components are discarded:

os.path.join("/upload/dir", "/etc/malicious") == "/etc/malicious"

This allows an attacker to bypass the intended upload directory and write files to arbitrary paths.

Affected Configuration

Projects are only affected if all of the following are true:
- UPLOAD_DIR is set - UPLOAD_KEEP_FILENAME is set to True - The uploaded file exceeds MAX_MEMORY_FILE_SIZE (triggering a flush to disk)

The default configuration is not vulnerable.

Impact

Arbitrary file write to attacker-controlled paths on the filesystem.

Mitigation

Upgrade to version 0.0.22, or avoid using UPLOAD_KEEP_FILENAME=True in project configurations.

Severity
8.6 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "python-multipart"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24486"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-26T23:28:05Z",
    "nvd_published_at": "2026-01-27T01:16:02Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nA Path Traversal vulnerability exists when using non-default configuration options `UPLOAD_DIR` and `UPLOAD_KEEP_FILENAME=True`. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename.\n\n### Details\n\nWhen `UPLOAD_DIR` is set and `UPLOAD_KEEP_FILENAME` is `True`, the library constructs the file path using `os.path.join(file_dir, fname)`. Due to the behavior of `os.path.join()`, if the filename begins with a `/`, all preceding path components are discarded:\n\n```py\nos.path.join(\"/upload/dir\", \"/etc/malicious\") == \"/etc/malicious\"\n```\n                        \nThis allows an attacker to bypass the intended upload directory and write files to arbitrary paths.                                         \n                                                                                                                                              \n#### Affected Configuration                                                                                                                      \n                                                                                                                                              \nProjects are only affected if all of the following are true:                                                                                     \n- `UPLOAD_DIR` is set\n- `UPLOAD_KEEP_FILENAME` is set to True\n- The uploaded file exceeds `MAX_MEMORY_FILE_SIZE` (triggering a flush to disk)\n\nThe default configuration is not vulnerable.                                                                                                \n                                                                                                                                              \n#### Impact                                                                                                                                   \n                                                                                                                                              \nArbitrary file write to attacker-controlled paths on the filesystem.                                                                        \n                                                                                                                                              \n#### Mitigation                                                                                                                                  \n                                                                                                                                              \nUpgrade to version 0.0.22, or avoid using `UPLOAD_KEEP_FILENAME=True` in project configurations.",
  "id": "GHSA-wp53-j4wj-2cfg",
  "modified": "2026-01-29T03:24:52Z",
  "published": "2026-01-26T23:28:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Kludex/python-multipart/security/advisories/GHSA-wp53-j4wj-2cfg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24486"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Kludex/python-multipart/commit/9433f4bbc9652bdde82bbe380984e32f8cfc89c4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Kludex/python-multipart"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Kludex/python-multipart/releases/tag/0.0.22"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Python-Multipart has Arbitrary File Write via Non-Default Configuration"
}



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