CVE-2026-12039 — Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution

CVE-2026-12039

Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
Docker / Docker Sandboxes	affected 0.13.0 before 0.33.0

CWE

CWE-923

References

https://docs.docker.com/ai/sandboxes/
https://github.com/docker/sbx-releases/releases/tag/v0.33.0

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.