PT-2026-50674 · Docker · Docker Sandboxes

Sophie Lemos · Published 2026-06-18 · Updated 2026-06-18 · CVE-2026-12039

Mitre

CVSS v4.0

5.7

Medium

Base vector

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

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.

Fix

Weakness Enumeration

CWE-923

Related Identifiers

CVE-2026-12039

Affected Products

Docker Sandboxes

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-12039 · Security Note
• https://github.com/docker/sbx-releases/releases/tag/v0.33.0 · Note
• https://docs.docker.com/ai/sandboxes · Note