CVE-2026-103916: Path traversal in Docker Sandboxes sbx cp

CVE-2026-103916 is a path traversal vulnerability in Docker Sandboxes sbx cp command that allows malicious containers to bypass confinement of the shared workspace. An attacker can create or replace a symlink in the workspace: when a trusted user subsequently executes a copy operation, the system can read files from the host outside the workspace into the container, or write container-controlled data to non-confined host paths using the permissions of the user invoking the command.

The CVSS score is 8.4 (high severity), with direct impact on data confidentiality and integrity. The vulnerability was publicly disclosed on November 3 2026 and officially registered in NVD. Social media signals on platforms like X indicate public awareness; no confirmed public exploits in GitHub repositories have been reported, however technical details of the flaw have been made public by the researcher.

Defenders must prioritize updating Docker Sandboxes to the correct version as soon as it becomes available. In the meantime it is advisable to limit access to shared workspaces, review logs of sbx cp operations for detected anomalies, suspicious symbols and unexpected access, and monitor container-to-host communication through syscall audit. Access permissions must be reviewed and the integrity of data read from shared workspaces verified.