rclone CVE-2026-88016

Exploitation requires all of the following to be true simultaneously: (1) the --links flag must be passed to rclone - this is non-default and not present in standard sync invocations; (2) the attacker must control the sync source contents, meaning they have write access to the remote storage provider or bucket being synced from; (3) a user must initiate the sync operation (UI:R); (4) for chown and chmod escapes, --metadata must additionally be enabled; modification-time escape occurs without --metadata via the normal directory sync workflow. Exploitation is limited to: non-default --links configuration, attacker-controlled source storage, active user triggering the sync, and platform support for the targeted metadata type (birth-time impact is skipped on platforms where it is unsettable). Default rclone usage without --links is not vulnerable.

The CVSS 7.1 vector (AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:L) correctly captures the multi-step exploitation chain: network-sourced attack, high complexity due to non-default flags and two-phase exploitation, low-privilege attacker controlling source storage, and required user interaction to initiate the sync. The scope-changed designation is accurate because successful exploitation modifies metadata of filesystem objects outside the sync destination boundary. No EPSS data was provided in the input, so probabilistic exploitation likelihood cannot be quantified beyond the structural signals. No CISA KEV listing exists and no public exploit code has been identified, making this lower urgency than the raw CVSS score implies - even a mid-sized municipal IT team in tczew using rclone for cloud backup workflows would face realistic risk only if they enable --links against an untrusted or attacker-controlled remote source. The practical attack surface is therefore narrowed to scenarios where an adversary controls the cloud storage bucket or remote endpoint being synced from, which limits opportunistic mass exploitation but makes targeted supply-chain-style attacks (malicious bucket contents) the primary concern. The high integrity sub-score is warranted given that arbitrary chown/chmod on out-of-scope files can meaningfully undermine host security posture.

An attacker who has write access to a cloud storage bucket (or controls a malicious rclone-compatible remote) uploads a crafted .rclonelink file targeting a sensitive directory such as /etc/cron.d or /home/admin/.ssh. When the victim operator runs rclone sync remote:malicious-bucket /destination --links --metadata, rclone materializes the symlink during the copy phase. The subsequent directory metadata phase then follows the planted symlink and calls os.Chown or os.Chmod on the target path outside the destination, potentially making it world-writable or reassigning ownership to an attacker-controlled UID. No public exploit code exists at time of analysis.