EUVD-2026-75587
GHSA-p569-5gjg-9cmj
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Unauthenticated network access yields anonymous read/write to the fixed backend (C:H/I:H, A:N), but the vulnerable RC serve-start-with-auth-proxy deployment is non-default, so AC:H.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
5DescriptionCVE.org
rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.70.0 until 1.75.1, the serve/start RC interface accepts per-server proxyOpt.AuthProxy settings, and the FTP and S3 constructors in cmd/serve/ftp/ftp.go and cmd/serve/s3/server.go incorrectly check the process-global proxy.Opt.AuthProxy value instead. When the global value is empty, the request-local authentication proxy is ignored: FTP falls back to the fixed filesystem with username anonymous and any password, while S3 with AuthKey serves the fixed RC fs rather than the backend selected by the proxy. The dedicated command-line servers that configure the global option are not affected. This issue is fixed in version 1.75.1.
AnalysisAI
Authentication/authorization bypass in rclone's dynamic serve interface (versions 1.70.0 through 1.75.0) lets remote attackers reach a fixed filesystem instead of the per-request backend the operator intended. When an FTP or S3 server is spun up via the serve/start RC (remote control) API with a per-server proxyOpt.AuthProxy, the FTP and S3 constructors mistakenly consult the empty process-global proxy.Opt.AuthProxy, so the request-local auth proxy is silently ignored: FTP accepts anonymous logins with any password against the fixed VFS, and S3 with AuthKey serves the fixed RC fs rather than the proxy-selected backend. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target to run an rclone FTP or S3 server that was created dynamically through the serve/start RC interface with a per-server proxyOpt.AuthProxy configured, while the process-global proxy.Opt.AuthProxy is empty (the default for RC-launched servers). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score is 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N), reflecting unauthenticated network access with high confidentiality and integrity impact but no availability impact - consistent with anonymous read/write to a fixed filesystem. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patch: upgrade to rclone 1.75.1 (https://github.com/rclone/rclone/releases/tag/v1.75.1), which introduces a shared proxy.Provider that correctly honors the per-server auth proxy for FTP, HTTP, and S3 (fix commit 739403963abf6f58003c2becd5f7c4ad0d644153). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all rclone instances running versions 1.70.0-1.75.0 and immediately restrict network access to FTP/S3 serve endpoints if exposed to untrusted networks. …
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Same weakness CWE-863 – Incorrect Authorization
View allSame technique Authentication Bypass
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External POC / Exploit Code
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