CVE-2026-79776 in rclone
Summary
by MITRE • 08/25/2026
rclone before 1.75.0 mounts the pprof debug handler as its own router route, bypassing the fail-closed authentication rule in the main handler. Attackers can access the /debug/pprof/cmdline endpoint unauthenticated to retrieve the full process argv including backend credentials.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/25/2026
The vulnerability identified in rclone versions prior to 1.75.0 represents a critical misconfiguration of HTTP routing and authentication middleware that allows for unauthorized information disclosure. Rclone is a popular command-line program for data transfer between cloud storage providers, often handling sensitive backend credentials such as API keys, access tokens, and secret passwords within its process environment or configuration files. The core issue stems from the way the application initializes its web server components during operation. Specifically, the pprof debug handler, which is part of Go's standard library for profiling and debugging running processes, was mounted directly onto the main HTTP router without being subjected to the same authentication checks applied to other endpoints. This architectural oversight creates a bypass in the fail-closed security model that rclone employs for its primary interface, where access should be denied by default unless explicitly authorized.
From a technical perspective, this flaw is classified under CWE-284 Improper Access Control and CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes. The pprof package provides several endpoints that expose internal state information about the running Go process. Among these, the /debug/pprof/cmdline endpoint returns the command-line arguments used to start the program. In many deployment scenarios, particularly when rclone is run with inline configuration or environment variable injection for credentials, these arguments may contain sensitive data such as remote storage passwords, OAuth client secrets, or service account keys. Because this specific route was registered independently of the main authentication middleware chain, it remained accessible without any form of identity verification or session validation. This effectively creates an unauthenticated backdoor into the application's runtime environment, allowing any network-accessible actor to query the process metadata directly.
The operational impact of this vulnerability is severe due to the nature of the data exposed. An attacker with network access to the rclone server can send a simple HTTP GET request to the /debug/pprof/cmdline endpoint and receive a plaintext response containing the full command line string. If the administrator has passed credentials via command-line flags, such as --password or --config parameters that include secrets, these values are immediately compromised. This leads directly to CWE-200 Exposure of Sensitive Information to an Unauthorized Actor. The compromise of these credentials can result in unauthorized access to cloud storage buckets, data exfiltration, and potential lateral movement if the same credentials are reused across other systems. Furthermore, because pprof endpoints often expose additional profiling data like stack traces or memory profiles, there is a risk that further sensitive context could be leaked through adjacent routes if they share similar routing misconfigurations, although the primary immediate threat is the exposure of command-line arguments containing secrets.
To mitigate this vulnerability and align with industry best practices for secure application design, it is imperative to upgrade rclone to version 1.75.0 or later, where the developers have corrected the routing logic to ensure that debug endpoints are either disabled by default in production builds or properly gated behind authentication mechanisms. For environments running older versions that cannot be immediately upgraded, administrators should disable the pprof handlers entirely if they are not actively required for debugging purposes. This can often be achieved by ensuring that no import of net/http/pprof is present or by explicitly unmounting those routes during server initialization. Additionally, security hardening practices dictate that sensitive information such as passwords and API keys should never be passed via command-line arguments, as these are visible in process listings like ps output and HTTP requests. Instead, administrators should utilize secure configuration files with restricted file permissions or environment variables managed by a secrets manager to ensure that credentials remain isolated from the application's public-facing interfaces. This approach aligns with ATT&CK technique T1504 Weak or Missing Authentication, addressing the root cause of unauthorized access through proper enforcement of authentication policies across all service endpoints.