CVE-2026-104102: copyparty FTP: upload outside defined volumes (limited path traversal)

Q: Which deployments are exposed to this issue?

Only deployments that explicitly enable FTP or FTPS are affected. The vulnerable upload handling applies to copyparty versions before 1.20.19.

Q: What access does an attacker need?

An attacker needs low-privileged authenticated access to the FTP or FTPS service. No user interaction is required, and the attacker can submit traversal paths as part of an upload.

Q: What can an attacker do outside configured volumes?

They can create a new file in locations where the copyparty process has write permission, even if those locations are outside configured copyparty volumes. They cannot use this issue to read files or overwrite existing files, and created filenames receive a randomized suffix.

Q: What is the risk if the uploaded file is not executed by copyparty?

Copyparty does not execute the created file, but unrelated software on the same host may process it. Exposure therefore depends on whether writable locations accessible to the copyparty process are monitored or consumed by other software.

Q: What should be done if an immediate upgrade is not possible?

Disable FTP and FTPS if they are not required, since they must be explicitly enabled for exploitation. Also restrict the copyparty process's write permissions so it cannot create files in sensitive locations outside intended volumes.

Published Oct 12, 2026

Updated

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.

Affected Software

1 affected component

copyparty copyparty<1.20.19

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade copyparty to a version that resolves this vulnerability.
Fixed in 1.20.19

Event History

Oct 12, 2026

CVE Published

via MITRE·06:32 PM

Data Sourced

via MITRE·06:32 PM

DescriptionWeakness

Data Sourced

via NVD·07:16 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Which deployments are exposed to this issue?

Only deployments that explicitly enable FTP or FTPS are affected. The vulnerable upload handling applies to copyparty versions before 1.20.19.

What access does an attacker need?

An attacker needs low-privileged authenticated access to the FTP or FTPS service. No user interaction is required, and the attacker can submit traversal paths as part of an upload.

What can an attacker do outside configured volumes?

They can create a new file in locations where the copyparty process has write permission, even if those locations are outside configured copyparty volumes. They cannot use this issue to read files or overwrite existing files, and created filenames receive a randomized suffix.

What is the risk if the uploaded file is not executed by copyparty?

Copyparty does not execute the created file, but unrelated software on the same host may process it. Exposure therefore depends on whether writable locations accessible to the copyparty process are monitored or consumed by other software.

What should be done if an immediate upgrade is not possible?

Disable FTP and FTPS if they are not required, since they must be explicitly enabled for exploitation. Also restrict the copyparty process's write permissions so it cannot create files in sensitive locations outside intended volumes.

CVE-2026-104102: copyparty FTP: upload outside defined volumes (limited path traversal)

Affected Software

Remediation

Event History

Frequently Asked Questions

Which deployments are exposed to this issue?

What access does an attacker need?

What can an attacker do outside configured volumes?

What is the risk if the uploaded file is not executed by copyparty?

What should be done if an immediate upgrade is not possible?

Company

Resources

Contact

Frequently Asked Questions

Which deployments are exposed to this issue?

What access does an attacker need?

What can an attacker do outside configured volumes?

What is the risk if the uploaded file is not executed by copyparty?

What should be done if an immediate upgrade is not possible?