CVE-2026-79776

rclone before 1.74.4 fails to mask special permission bits when applying source-supplied mode metadata in the local backend, allowing attackers to set setuid/setgid bits on attacker-controlled files. When copying with metadata preservation from an untrusted remote, attackers can plant a setuid binary that escalates privileges to root if rclone runs as root.

rclone before v1.75.0 fails to sanitize IBM IAM bearer tokens and SSE-C encryption keys during S3 redirect callbacks, allowing credentials to be preserved across scheme or host changes. Attackers observing network traffic from a trusted endpoint can capture reusable IBM IAM tokens on same-host HTTPS-to-HTTP downgrades or SSE-C keys on cross-origin redirects to access protected S3 objects.

rclone before v1.75.0 contains a denial of service vulnerability in the WebDAV TUS creation handler that dereferences a nil response before checking for transport errors. A malicious or compromised configured endpoint can reset connections during TUS uploads to trigger a panic that terminates unrecovered goroutines and halts unrelated work in long-lived processes.

Rclone versions 1.46.0 through 1.74.2 have a vulnerability in server mode (rcd --rc-serve) that allows unauthenticated GET and HEAD requests to execute arbitrary system commands. An attacker can craft a URL containing remote storage configuration that executes local commands during initialization.

In Rclone from version 1.48.0 to 1.73.4, the RC endpoint `operations/fsinfo` is exposed without `AuthRequired: true` and accepts attacker-controlled `fs` input. An unauthenticated attacker can exploit this to execute arbitrary local commands on the server via the WebDAV backend, which runs `bearer_token_command` during initialization.

In Rclone, the RC endpoint `options/set` is exposed without `AuthRequired: true`, allowing modification of global runtime configuration. An unauthenticated attacker can set `rc.NoAuth=true`, disabling the authorization gate for many RC methods that normally require authentication, leading to unauthorized access to sensitive administrative functionality.

rclone before 1.74.4 fails to strip the X-Amz-Security-Token header when an S3 redirect changes scheme from HTTPS to HTTP on the same host. Attackers can intercept plaintext HTTP traffic to capture AWS STS session tokens sent in request headers.

rclone serve s3 before version 1.74.4 contains a path traversal vulnerability that allows attackers to read and overwrite root-level files by using dot-dot segments in S3 object keys. Attackers can send requests with object keys like '../root-secret.txt' to escape the bucket namespace and access files in the serve root directory.

rclone versions before v1.75.0 fail to reject transport downgrades in redirect handling, allowing Basic authorization and Cookie headers to be replayed over plaintext HTTP after same-host HTTPS-to-HTTP redirects. An on-path attacker observing the plaintext hop can capture and reuse credentials to perform WebDAV operations with the compromised account's permissions.

rclone before v1.75.0 includes full Go stack traces in RC API error responses when panics occur. Attackers can trigger panics to leak internal file paths, module versions, goroutine states, and memory addresses.