CVE-2026-88046: rclone: source object names can escape the configured root on upload
rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.1, rclone core does not reject parent-directory segments in source Object.Remote() values before fs/list, fs/walk, fs/sync, and fs/operations pass those values to destination backends. A flat-keyspace source object store populated with native non-rclone tooling can contain a raw .. key segment, and affected b2, swift, qingstor, oracleobjectstorage, internetarchive, smb, storj, sftp, webdav, ftp, filelu, shade, and sia destinations use path.Join(root, remote) before EncodeDot can neutralize the segment. A copy or upload can therefore escape the configured root into another bucket, share, or path reachable by the victim credential, with sftp and smb potentially reaching other filesystem or share locations under the same login authority. This issue is fixed in version 1.75.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
rcloneto a version that resolves this vulnerability.Fixed in 1.75.1
Event History
Frequently Asked Questions
Which deployments are exposed to unintended writes outside the configured destination root?
Deployments using rclone before 1.75.1 are exposed when copying or uploading from a flat-keyspace source store that contains an object name with a raw ".." path segment, and the destination is b2, swift, qingstor, oracleobjectstorage, internetarchive, smb, storj, sftp, webdav, ftp, filelu, shade, or sia.
What must an attacker control or influence to exploit this issue?
An attacker needs to cause rclone to process a source object whose Object.Remote() value includes a parent-directory segment. Such object names can exist in flat-keyspace source stores when populated using native non-rclone tooling.
How far can an escaped upload reach?
The write can reach another bucket, share, or path that is accessible to the credentials used by the rclone operation. For SFTP and SMB destinations, it may reach other filesystem or share locations under the same login authority.
What is the remediation?
Upgrade rclone to version 1.75.1, which fixes the handling of parent-directory segments in source object names before they are passed to destination backends.