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The vulnerability resides within the optional FTP and FTPS server components of the copyparty portable file server application. When explicitly enabled via configuration options, the FTP or FTPS service fails to properly confine upload destinations to designated and configured copyparty volumes, allowing authenticated or permitted users to traverse paths and upload files outside expected boundaries. However, the vulnerability possesses several strict built-in limitations that mitigate its direct impact. It functions exclusively as an upload mechanism, meaning attackers cannot read, download, overwrite, or append to existing files. Furthermore, output filenames automatically receive a randomized suffix, and copyparty itself refuses to execute arbitrary uploaded files as code by default. The primary security concern involves indirect risks where unrelated software running on the same host machine processes the newly created files. Under worst-case assumptions, if the host system runs secondary applications that automatically execute newly dropped files, and if the copyparty process holds sufficient filesystem permissions to write to those specific directories, an attacker could leverage this interaction to achieve broader system compromise. Remediation requires upgrading the copyparty application to version 1.20.19 or higher, where proper path handling constraints are enforced.
DailyCVE Form:
Platform: Copyparty
Version: <1.20.19
Vulnerability : Path Traversal
Severity: Medium
date: 2026-10-12
Prediction: 2026-10-12
What Undercode Say:
Bash Commands and Codes:
Enable FTP explicitly in configuration if required, or disable FTP/FTPS services python3 -m copyparty --ftpd Upgrade copyparty to the patched version pip install --upgrade copyparty
Exploit: (Educational Purposes!)
The exploit involves connecting to an enabled FTP or FTPS server interface on copyparty and supplying crafted path traversal sequences during file storage operations. Because upload destination validation is flawed prior to version 1.20.19, the server writes the payload outside the virtual volume root. The exploit is constrained because filenames receive randomized suffixes, existing files cannot be overwritten, and copyparty will not execute the resulting payload natively. Success relies entirely on secondary software on the shared host reading and executing the rogue file.
Protection:
Disable the optional FTP and FTPS server features in the copyparty configuration if they are not actively required for operations. Ensure that the copyparty process runs under a restricted service account with minimal filesystem privileges to prevent writing to sensitive directories or application paths used by other software. Immediately upgrade the copyparty server environment to version 1.20.19 or later to permanently resolve the path handling flaw.
Impact:
Enables remote users to bypass volume boundary restrictions and upload files to arbitrary directories on the host filesystem where the copyparty process has write permissions. While copyparty does not execute these files, successful exploitation could interact with vulnerable third-party software running locally on the same machine, potentially resulting in arbitrary code execution or unauthorized file placement under worst-case system privilege configurations.
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Sources:
Reported By: github.com
Extra Source Hub:
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