CVE-2026-116192 in Rclone
Summary
by MITRE • 10/25/2026
rclone from 1.37 before 1.74.2 contains a server-side request forgery vulnerability that allows unauthenticated attackers to redirect http and netstorage backend requests by supplying a double-slash root on an existing named remote via --rc-serve. Attackers can make HEAD/GET requests to attacker-chosen hosts to read responses, capture configured custom headers, or obtain valid NetStorage request signatures.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 10/25/2026
The vulnerability identified in rclone versions prior to 1.74.2 represents a critical server-side request forgery flaw that exploits the handling of remote storage configurations when utilizing the --rc-serve feature. This component allows users to serve files from various cloud storage backends via an HTTP interface, effectively turning rclone into a proxy or gateway for accessing stored data. The core technical deficiency lies in how the application processes URL paths and backend routing logic when constructing requests to upstream storage providers such as HTTP-based services or NetStorage systems. Specifically, the vulnerability is triggered by supplying a double-slash root sequence on an existing named remote configuration. This malformed input bypasses expected validation checks that are designed to ensure requests remain within the boundaries of the configured storage provider, allowing the application to interpret subsequent path segments as part of the target host rather than as internal routing parameters.
From a technical perspective, this flaw enables unauthenticated attackers to redirect outgoing HTTP and NetStorage backend requests to arbitrary destinations controlled by the attacker. By manipulating the request structure through the double-slash injection, an adversary can force rclone to issue HEAD or GET requests to externally chosen hosts. This capability transforms the vulnerable instance into a powerful amplification vector for SSRF attacks. The impact extends beyond simple redirection; because rclone often operates with elevated privileges relative to cloud storage APIs and may retain active authentication tokens or session cookies associated with the configured remotes, an attacker can leverage this mechanism to exfiltrate sensitive data. Furthermore, the vulnerability allows attackers to capture custom headers that are automatically appended by rclone during request transmission. These headers frequently contain authorization credentials, API keys, or other metadata essential for accessing protected resources on behalf of legitimate users.
In environments utilizing NetStorage backends, such as those provided by Akamai, the consequences are particularly severe due to the nature of signed requests. The vulnerability permits attackers to obtain valid NetStorage request signatures generated by rclone. These cryptographic signatures authenticate subsequent requests to the storage provider without requiring additional credentials for each individual operation. An attacker who captures these signatures can replay them against the target cloud service to read, modify, or delete data stored in the associated buckets or containers. This effectively grants unauthorized access to all resources accessible via that specific remote configuration, leading to potential data breaches and integrity violations across the organization's cloud infrastructure.
This vulnerability aligns with CWE-918, which describes Server-Side Request Forgery (SSRF), where a web application fetches a specified resource from a user-supplied URL but fails to sufficiently validate whether that request should be allowed to proceed. Additionally, it maps to MITRE ATT&CK technique T1572, Protocol Tunneling, as the attacker uses legitimate protocols and services to establish covert communication channels or exfiltrate data. The exploitation path also relates to CWE-436, Interpretation Conflict, where ambiguous input interpretation leads to unintended behavior in security-critical components like URL parsing and routing logic.
To mitigate this risk, organizations must immediately upgrade rclone to version 1.74.2 or later, which includes patches that enforce stricter validation of remote paths and prevent the double-slash root injection from triggering unauthorized redirections. Administrators should also review their --rc-serve configurations to ensure they are not exposed to untrusted networks without proper authentication mechanisms enabled via the rc-auth flag. Implementing network-level controls such as firewall rules or reverse proxies that restrict outbound connections from rclone instances can provide an additional layer of defense, limiting the ability of any potential SSRF exploit to reach external malicious hosts. Regular auditing of cloud storage access logs is also recommended to detect any anomalous request patterns indicative of signature replay attacks resulting from this vulnerability.