CVE-2026-12039
Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution
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.
INFO
Published Date :
June 18, 2026, 2:17 p.m.
Last Modified :
June 30, 2026, 6:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | 686469e6-3ff6-451b-ab8b-cf5b9e89401e | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Implement egress filtering for DNS traffic.
- Validate DNS resolution policies.
- Apply network allowlist to DNS queries.
- Update DNS server configuration.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-12039.
| URL | Resource |
|---|---|
| https://docs.docker.com/ai/sandboxes/ | |
| https://github.com/docker/sbx-releases/releases/tag/v0.33.0 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12039 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-12039
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-12039 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12039 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jun. 30, 2026
Action Type Old Value New Value Changed Affected [{'vendor': 'Docker', 'product': 'Docker Sandboxes', 'versions': [{'status': 'affected', 'version': '0.13.0', 'lessThan': '0.33.0', 'versionType': 'semver'}], 'platforms': ['MacOS', 'Linux', 'Windows'], 'defaultStatus': 'unaffected'}] [{'cpes': ['cpe:2.3:a:docker:sandboxes:*:*:*:*:*:*:*:*'], 'vendor': 'Docker', 'product': 'Docker Sandboxes', 'versions': [{'status': 'affected', 'version': '0.13.0', 'lessThan': '0.33.0', 'versionType': 'semver'}], 'platforms': ['MacOS', 'Linux', 'Windows'], 'defaultStatus': 'unaffected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-12039', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-18T15:00:00.773890Z'} -
New CVE Received by [email protected]
Jun. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Docker', 'product': 'Docker Sandboxes', 'versions': [{'status': 'affected', 'version': '0.13.0', 'lessThan': '0.33.0', 'versionType': 'semver'}], 'platforms': ['MacOS', 'Linux', 'Windows'], 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 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 Added CWE CWE-923 Added Reference https://docs.docker.com/ai/sandboxes/ Added Reference https://github.com/docker/sbx-releases/releases/tag/v0.33.0