HOMEVULNERABILITIESCVE-2026-12039
MEDIUM

CVE-2026-12039

CWE-923Published: June 18, 2026· Updated: Jun 22, 2026

5.7
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2026-12039 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeX
Impact
Confidentiality
Integrity
Availability
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected Vendors & Products

Mentioned vendors (from description):
Docker
CPE data not yet available in NVD for this CVE.

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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All References (2)

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

Quick Facts

CVE IDCVE-2026-12039
CVSS Score5.7 / 10
SeverityMEDIUM
WeaknessCWE-923
CISA KEVNo
PublishedJun 18, 2026

Related CVEs (CWE-923)

CVE-2026-34205
9.6
CVE-2026-23664
7.5
CVE-2026-55655
6.1
CVE-2025-36438
5.5
CVE-2025-36145
5.3
CVE-2025-36180
5.3

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-12039 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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