Home

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.

PUBLISHED Reserved 2026-06-11 | Published 2026-06-18 | Updated 2026-06-18 | Assigner Docker




MEDIUM: 5.7CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-923: Improper Restriction of Communication Channel to Intended Endpoints

Product status

Default status
unaffected

0.13.0 (semver) before 0.33.0
affected

Credits

Sophie Lemos finder

References

docs.docker.com/ai/sandboxes/ product

github.com/docker/sbx-releases/releases/tag/v0.33.0 release-notes

cve.org (CVE-2026-12039)

nvd.nist.gov (CVE-2026-12039)

Download JSON