9001 copyparty up to 1.20.18 FTP Upload Path path traversal

Summaryinfo

A vulnerability, which was classified as problematic, has been found in 9001 copyparty up to 1.20.18. This impacts an unknown function of the component FTP Upload Path Handler. The manipulation leads to path traversal. This vulnerability is listed as CVE-2026-104102. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in 9001 copyparty up to 1.20.18 and classified as problematic. This issue affects an unknown functionality of the component FTP Upload Path Handler. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. 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. Impacted is integrity. The summary by CVE is:

copyparty is a portable file server. Prior to 1.20.19, FTP upload path handling does not confine destinations to configured copyparty volumes. When FTP or FTPS is explicitly enabled, a low-privileged authenticated user can submit traversal paths during upload to create a new file outside configured volumes wherever the copyparty process has write permission. The attacker cannot read or overwrite files, the output name receives a randomized suffix, and copyparty does not execute the file; however, unrelated software on the same host could process the newly created file. This issue is fixed in version 1.20.19.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-104102 since 10/01/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 1.20.19 eliminates this vulnerability.

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Productinfo

Vendor

• 9001

Name

• copyparty

Version

• 1.20.0
• 1.20.1
• 1.20.2
• 1.20.3
• 1.20.4
• 1.20.5
• 1.20.6
• 1.20.7
• 1.20.8
• 1.20.9
• 1.20.10
• 1.20.11
• 1.20.12
• 1.20.13
• 1.20.14
• 1.20.15
• 1.20.16
• 1.20.17
• 1.20.18

Website

• Product: https://github.com/9001/copyparty/

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