Vulnerability Description
Docker Sandboxes (sbx) enforces an HTTP/S-only egress allowlist but does not apply it to DNS resolution: the per-network embedded DNS server forwards any queried name to the host resolver whenever the network is internet-connected, without consulting the policy. A workload inside a sandbox, which the threat model treats as untrusted, can therefore encode data into DNS labels for an attacker-controlled domain and exfiltrate it through a DNS covert channel, bypassing the configured allowlist.
Related Weaknesses (CWE)
References
FAQ
What is CVE-2026-12039?
CVE-2026-12039 is a documented vulnerability. Docker Sandboxes (sbx) enforces an HTTP/S-only egress allowlist but does not apply it to DNS resolution: the per-network embedded DNS server forwards any queried name to the host resolver whenever the...
How severe is CVE-2026-12039?
CVSS scoring is not yet available for CVE-2026-12039. Check NVD for updates.
Is there a patch for CVE-2026-12039?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.