CVE-2026-88044
Received Received - Intake

Rclone Remote Command Execution via AuthProxy Misconfiguration

Publication date: 2026-09-10

Last updated on: 2026-09-10

Assigner: GitHub, Inc.

Description
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.

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Meta Information

Published
2026-09-10
Last Modified
2026-09-10
Generated
2026-09-10
AI Q&A
2026-09-10
EPSS Evaluated
N/A
NVD
CVE-2026-88044
EUVD
EUVD-2026-75587

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
rclone rclone From 1.70.0 (inc) to 1.75.1 (exc)
rclone rclone 1.75.1

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

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Executive Summary

This is an authentication bypass vulnerability in rclone versions 1.70.0 to 1.75.1. When using per-server proxy authentication settings for FTP or S3 remote control interfaces, the software incorrectly checks a global proxy setting instead of the request-specific setting. This allows unauthorized access to files.

Detection Guidance

Check if your rclone version is between 1.70.0 and 1.75.0. Run 'rclone version' to verify. Inspect FTP or S3 server configurations for per-server proxyAuth settings. Monitor logs for anonymous FTP logins or unexpected S3 key access patterns.

Impact Analysis

An attacker could connect to an exposed FTP or S3 listener and gain access without valid credentials. For FTP, they can log in anonymously and perform read, write, or delete operations. For S3, any authenticated key can access a fixed filesystem instead of the intended backend.

Compliance Impact

This vulnerability could lead to unauthorized data access, violating confidentiality and integrity requirements in GDPR and HIPAA. It may result in data breaches, unauthorized modifications, or deletions, potentially leading to regulatory penalties and loss of compliance.

Mitigation Strategies

Upgrade rclone to version 1.75.1 or later immediately. Disable FTP and S3 RC interfaces if not required. Review server configurations to ensure global proxyAuth settings are correctly applied. Restrict network access to FTP/S3 listeners to trusted IPs.

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