---
cve: "CVE-2026-12039"
severity: "MEDIUM"
cvss: 5.7
epss: "0.1%"
vendor: "Docker"
kev: false
exploited: false
published: "2026-06-18 13:48:14"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T00:49:29+02:00"
---

# CVE-2026-12039

> 5.7 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- e4809b108ff941fbd3dc8ab1edd8755af78ddc07 (Commit)

## Referenzen

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

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-12039) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_