CVE-2026-88017

/// Technical description

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.64.0 until 1.75.1, the FTP auth-proxy driver in cmd/serve/ftp/ftp.go stores one obscured password per username in the server-wide userPass map[string]string instead of binding the credential or VFS to the authenticated session. If two accepted credentials use the same username but resolve to different proxy backends, a later CheckPasswd login overwrites userPass[user], and subsequent getVFS operations on the first session are reauthorized with the later password. The first session can then read, create, overwrite, rename, or delete objects using the second credential’s backend authority. Exploitation requires the later same-username login to occur while the first session remains open. This issue is fixed in version 1.75.1.

/// Remediation

Check the references section for vendor advisories and patches from rclone. Update rclone to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// Affected products

/// References