CVE-2026-12039: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-4crj-qc6g-g3xj
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CWE-923
Published
Advisory Summary

CVE-2026-12039 is a MODERATE security vulnerability vulnerability (CWE-923: Improper Restriction of Communication Channel to Intended Endpoints) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-12039 at a Glance

CVE Identifier CVE-2026-12039
GHSA Identifier GHSA-4crj-qc6g-g3xj
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-923: Improper Restriction of Communication Channel to Intended Endpoints
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-12039

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-12039, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-923: Improper Restriction of Communication Channel to Intended Endpoints, where the product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-12039 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12039
docs.docker.com/ai/sandboxes WEB
https://docs.docker.com/ai/sandboxes
Software Release RELEASE
https://github.com/docker/sbx-releases/releases/tag/v0.33.0

Frequently Asked Questions

What is CVE-2026-12039?
CVE-2026-12039 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-923: Improper Restriction of Communication Channel to Intended Endpoints.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-12039?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-12039?
CVE-2026-12039 is classified under CWE-923: Improper Restriction of Communication Channel to Intended Endpoints (The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.).
How can I check Maven dependencies for CVE-2026-12039?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4crj-qc6g-g3xj",
  "modified" : "2026-06-18T15:32:02Z",
  "published" : "2026-06-18T15:32:02Z",
  "aliases" : [ "CVE-2026-12039" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-12039"
  }, {
    "type" : "WEB",
    "url" : "https://docs.docker.com/ai/sandboxes"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/docker/sbx-releases/releases/tag/v0.33.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-923" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-06-18T14:17:20Z"
  }
}