Description

OpenList a file list program that supports multiple storage. Prior to 4.2.3, OpenList's offline-download feature at POST /api/fs/add_offline_download with tool: "SimpleHttp" accepts an attacker-supplied URL and saves its bytes under a per-task temporary directory before transferring them to the user's destination storage. The temporary filename comes from the attacker-controlled Content-Disposition header, is passed from parseFilenameFromContentDisposition in internal/offline_download/http/util.go to filepath.Join(task.TempDir, filename) in SimpleHttp.Run in internal/offline_download/http/client.go, and is opened with os.Create without a containment check. Because filepath.Join cleans .. segments, a non-admin user with PermAddOfflineDownload on any path can traverse out of task.TempDir and create, truncate, or overwrite any file writable by the OpenList process whose parent directory already exists. The server/handles/offline_download.go AddOfflineDownload route uses normal user authentication rather than AuthAdmin, and local-storage destinations fall through tryPutUrl in internal/offline_download/tool/add.go to the vulnerable SimpleHttp.Run path. This issue is fixed in version 4.2.3.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-03T17:17:23.757Z",
  "pubdate": "2026-09-03T17:17:23.757Z",
  "executiveSummary": "OpenList versions prior to 4.2.3 contain a critical path traversal vulnerability within the offline-download feature, specifically in the 'SimpleHttp' download tool.\nThe vulnerability originates from improper neutralization of user-supplied input used in file system operations. An attacker can manipulate the Content-Disposition header to escape the designated temporary directory, allowing for arbitrary file creation, truncation, or overwriting on the host system.\nAny authenticated user possessing the 'PermAddOfflineDownload' permission can exploit this flaw. Since the application fails to perform necessary containment checks before executing os.Create, the process will write data to any location accessible by the service account's filesystem privileges.\nThe impact is significant, as it may lead to unauthorized system modification, data destruction, or potential remote code execution if sensitive configuration files, binaries, or SSH authorized keys are targeted. This vulnerability highlights the risks associated with trusting attacker-provided metadata during file processing operations.\nImmediate remediation involves upgrading to version 4.2.3 or later to ensure proper sanitization of file paths.",
  "technicalDetails": "The vulnerability resides in the interaction between 'parseFilenameFromContentDisposition' in 'internal/offline_download/http/util.go' and 'SimpleHttp.Run' located in 'internal/offline_download/http/client.go'.\nWhen a user initiates an offline download via 'POST /api/fs/add_offline_download' using the 'SimpleHttp' tool, the application retrieves a remote file and prepares to store it in a per-task temporary directory. The filename used for the local storage operation is extracted directly from the 'Content-Disposition' header provided by the remote server.\nThe 'filepath.Join' function is utilized to construct the final file path by combining 'task.TempDir' and the extracted filename. Crucially, 'filepath.Join' evaluates and cleans path traversal sequences such as '../'. Because there is no subsequent validation to ensure the resulting path remains within the boundaries of 'task.TempDir', the application allows the file handle to be opened outside the intended sandbox.\nThe 'os.Create' function is then invoked on the attacker-controlled path. This operation can overwrite existing files, truncate them to zero length, or create new files in directories where the OpenList service process has write permissions.\nThe attack flow is as follows: 1) An attacker authenticates to OpenList and confirms possession of the 'PermAddOfflineDownload' permission. 2) The attacker sets up a malicious server that hosts a file and returns a 'Content-Disposition' header with a crafted filename attribute containing multiple '../' sequences (e.g., 'filename=../../../etc/cron.d/malicious'). 3) The attacker triggers the 'POST /api/fs/add_offline_download' endpoint, providing the URL to their malicious server. 4) OpenList fetches the remote headers, parses the malicious filename, and joins it with the task directory. 5) The application attempts to create the file at the traversed path. 6) The underlying operating system grants the file handle based on the effective permissions of the OpenList process.\nThis vulnerability is particularly dangerous because the affected route does not require administrative privileges, significantly expanding the pool of potential attackers to any standard user."
}