CVE-2026-12039: medium-severity vulnerability in Docker Sandboxes
Docker Sandboxes network egress allowlist bypass via unfiltered DNS resolution
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.7epss 0.1%
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.
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
Affected products
Docker · Docker SandboxesRelated CVEs — Docker Sandboxes
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