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CVE-2026-12039 (GCVE-0-2026-12039)

Vulnerability from cvelistv5 – Published: 2026-06-18 13:48 – Updated: 2026-08-13 13:33
VLAI
Title
Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution
Summary
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
5.7 (Medium)
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
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-18 15:00 UTC
CWE
  • CWE-923 - Improper Restriction of Communication Channel to Intended Endpoints
Assigner
References
Impacted products
Vendor Product Version CPE status
Docker Docker Sandboxes Affected: 0.13.0 , < 0.33.0 (semver)
    cpe:2.3:a:docker:docker_sandboxes:*:*:*:*:*:*:*:*
Create a notification for this product.
Credits
Sophie Lemos
Show details on NVD website
To clipboard 

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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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