Exploitation of Docker Sandboxes' DNS Resolution Mechanism
CVE-2026-12039

5.7MEDIUM

Key Information:

Vendor

Docker

Status
Docker Sandboxes
Vendor
CVE Published:
18 June 2026

What is CVE-2026-12039?

Docker Sandboxes enforce an HTTP/S-only egress allowlist; however, this policy does not extend to DNS resolution. When the network is connected to the internet, the embedded DNS server queries names without adhering to the defined policy, allowing untrusted workloads to exploit this oversight. An attacker can encode data into DNS labels for their domain and exfiltrate sensitive information through a covert DNS channel, bypassing security measures designed to protect the environment.

Affected Version(s)

Docker Sandboxes MacOS 0.13.0 < 0.33.0

References

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

CVSS V4

Score:
5.7
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Sophie Lemos
.