# CVE-2026-12039

## Summary

- **CVE ID:** CVE-2026-12039
- **Severity:** MEDIUM
- **CVSS Score:** 5.7 (CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-923
- **Published:** Jun 18, 2026
- **Last Modified:** Aug 13, 2026

## 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.

## Affected Products

- Docker — Docker Sandboxes (0.13.0)

## References

- [CNA](https://docs.docker.com/ai/sandboxes/)
- [CNA](https://github.com/docker/sbx-releases/releases/tag/v0.33.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.15%
- **EPSS Percentile:** 4.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._