CVE-2026-71310

Received Received - Intake

Memory Exhaustion in Rclone via Proxy CONNECT Headers

Publication date: 2026-08-05

Last updated on: 2026-08-05

Assigner: GitHub, Inc.

Description

rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.0, the shared HTTP CONNECT helper in lib/proxy/http.go parses proxy CONNECT responses with http.ReadResponse over an unrestricted buffered reader, allowing a malicious or compromised configured proxy, or an active on-path actor controlling a plaintext HTTP proxy hop, to send oversized headers that grow memory until the rclone process fails. The affected helper is used by FTP and SFTP proxy connections, and SFTP reaches the parser before SSH server authentication, so target host key validation does not constrain a malicious proxy. This issue is fixed in 1.75.0.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-05

Last Modified

2026-08-05

Generated

2026-08-06

AI Q&A

2026-08-06

EPSS Evaluated

N/A

NVD

CVE-2026-71310

EUVD

EUVD-2026-53615

Affected Vendors & Products

Vendor	Product	Version / Range
rclone	rclone	to 1.75.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-400	The product does not properly control the allocation and maintenance of a limited resource.
CWE-770	The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

Executive Summary

rclone before 1.75.0 has a memory exhaustion issue in its HTTP CONNECT proxy helper. The helper uses http.ReadResponse on an unrestricted buffered reader to parse proxy CONNECT responses. A malicious proxy or on-path attacker can send oversized headers, causing the rclone process to consume excessive memory and fail.

Detection Guidance

Detecting this vulnerability requires checking the version of rclone installed on your system. Run 'rclone version' to see the current version. If it is below 1.75.0, the system is vulnerable.

Impact Analysis

This vulnerability can cause rclone to crash due to memory exhaustion. If you use rclone with FTP or SFTP proxy connections, a compromised or malicious proxy could disrupt your file transfers. SFTP connections are vulnerable before server authentication, so host key validation does not prevent exploitation.

Mitigation Strategies

Upgrade rclone to version 1.75.0 or later immediately. This can be done by downloading the latest version from the official rclone website or using your package manager to update.

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