CVE-2026-88046

rclone from 1.75.0 until 1.75.1, in the serve S3 streamed multipart path, passes attacker-controlled contentLength to multipart.NewRW().Reserve before reading request-body bytes. A network client can retain or multiply these reservations without sending the declared body, exhausting process or host memory or permanently blocking request handlers. This is fixed in 1.75.1.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.64.0 until 1.75.1, the FTP auth-proxy driver in cmd/serve/ftp/ftp.go stores one obscured password per username in the server-wide userPass map[string]string instead of binding the credential or VFS to the authenticated session. If two accepted credentials use the same username but resolve to different proxy backends, a later CheckPasswd login overwrites userPass[user], and subsequent getVFS operations on the first session are reauthorized with the later password. The first session can then read, create, overwrite, rename, or delete objects using the second credential’s backend authority. Exploitation requires the later same-username login to occur while the first session remains open. This issue is fixed in version 1.75.1.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.1, when backend/local runs with --links, a source .rclonelink object can plant a symlink in the destination and later directory metadata is applied through that path. MkdirMetadata, writeMetadataToFile, and setTimes operate when Directory.translatedLink=false, so os.Chown, os.Chmod, os.Chtimes, and birth-time handling can bypass os.Root confinement and follow the symlink. An attacker controlling source contents can therefore apply selected ownership, permissions, modification times, or birth times to a file or directory outside the destination, with --metadata required for chmod and chown while modification time is applied by the normal directory workflow. This issue is fixed in version 1.75.1.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.1, backend/local with --links or links=true exposes symlink targets as .rclonelink objects, and fs.RangeOption.Decode can pass an unchecked positive Range start through Object.Open and openTranslatedLink. The function slices the target string as linkdst[offset:], so a Range start larger than the target length causes a deterministic slice-bounds panic when lib/http/serve exposes the object through HTTP or WebDAV. Go net/http normally recovers the panic per connection, causing request-level denial of service rather than terminating the entire process. This issue is fixed in version 1.75.1.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.72.0 until 1.75.1, the archive ZIP backend method (*Fs).readZip in backend/archive/zip/zip.go accepts archive/zip.File.Name values from an untrusted central directory and exposes cleaned entry names without ensuring that they remain inside the archive namespace. Entries such as ../../etc/cron.d/evil can survive path.Clean and become Object.Remote() values that fs/sync and fs/operations use as destination-relative paths, allowing rclone copy or sync to write outside the selected destination on backends that do not independently confine the path. The non-empty root check also used strings.HasPrefix without a path boundary, so root foo could incorrectly include sibling foobar entries. This issue is fixed in version 1.75.1.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.49.0 until 1.75.1, the HTTP backend attaches headers configured through --http-headers or headers= to requests in backend/http/http.go, while its fshttp.NewClient client follows redirects without a backend-specific http.Client.CheckRedirect policy. A configured remote that redirects to another host can therefore cause custom secrets such as X-Api-Key to be resent to that untrusted destination, and a same-host HTTPS-to-HTTP redirect can expose Authorization or Cookie headers in cleartext. Listing, stat, download, mount, and serve operations can trigger the leak during normal use. This issue is fixed in version 1.75.1.

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 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.