{"id":"CVE-2026-12039","state":"PUBLISHED","title":"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.","publishedAt":"2026-06-18T13:48:14.682Z","updatedAt":"2026-08-13T13:33:35.581Z","severity":{"score":5.7,"label":"Medium","version":"4.0","vector":"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","source":"Docker"},"assigner":"Docker","products":["Docker Docker Sandboxes"],"affected":[{"vendor":"Docker","product":"Docker Sandboxes","defaultStatus":"unaffected","versions":[{"version":"0.13.0","status":"affected","lessThan":"0.33.0","versionType":"semver"}],"platforms":["MacOS","Linux","Windows"],"cpes":["cpe:2.3:a:docker:docker_sandboxes:*:*:*:*:*:*:*:*"]}],"references":["https://docs.docker.com/ai/sandboxes/","https://github.com/docker/sbx-releases/releases/tag/v0.33.0"],"weaknesses":["CWE-923"],"ingestedAt":"2026-10-29T20:10:52.580Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/12xxx/CVE-2026-12039.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-12039","state":"PUBLISHED","datePublished":"2026-06-18T13:48:14.682Z","dateUpdated":"2026-08-13T13:33:35.581Z","assignerShortName":"Docker","assignerOrgId":"686469e6-3ff6-451b-ab8b-cf5b9e89401e","dateReserved":"2026-06-11T19:23:44.967Z"},"containers":{"cna":{"title":"Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Docker","product":"Docker Sandboxes","defaultStatus":"unaffected","versions":[{"version":"0.13.0","status":"affected","lessThan":"0.33.0","versionType":"semver"}],"platforms":["MacOS","Linux","Windows"],"cpes":["cpe:2.3:a:docker:docker_sandboxes:*:*:*:*:*:*:*:*"]}],"references":[{"url":"https://docs.docker.com/ai/sandboxes/","tags":["product"]},{"url":"https://github.com/docker/sbx-releases/releases/tag/v0.33.0","tags":["release-notes"]}],"metrics":[{"cvssV4_0":{"version":"4.0","vectorString":"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","baseScore":5.7,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","exploitMaturity":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-923","description":"CWE-923: Improper Restriction of Communication Channel to Intended Endpoints","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"Docker","orgId":"686469e6-3ff6-451b-ab8b-cf5b9e89401e","dateUpdated":"2026-08-13T13:33:35.581Z"},"credits":[{"lang":"en","type":"finder","value":"Sophie Lemos"}],"impacts":[{"capecId":"CAPEC-554","descriptions":[{"lang":"en","value":"CAPEC-554 Functionality Bypass"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-18T15:00:00.773890Z","id":"CVE-2026-12039","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-18T15:00:24.095Z"}}]}}}