rclone: FTP cross-session auth-proxy backend confusion

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-88017
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-10 16:18:08 UTC
Updated2026-09-10 16:18:08 UTC
Descriptionrclone 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.

Risk And Classification

Primary CVSS: v3.1 7.3 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Problem Types: CWE-488 | CWE-488 CWE-488: Exposure of Data Element to Wrong Session

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.3HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
3.1CNADECLARED7.3HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Rclone Rclone affected >= 1.64.0, < 1.75.1 Not specified

References

ReferenceSourceLinkTags
github.com/rclone/rclone/security/advisories/GHSA-c476-6w5q-jw77 [email protected] github.com
github.com/rclone/rclone/releases/tag/v1.75.1 [email protected] github.com
github.com/rclone/rclone/commit/c6af0b57c2b4af848bc968c2b407354476184b99 [email protected] github.com
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