CVE-2026-12039
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.
Scoring
- Severity
- MEDIUM
- CVSS base score
- 5.7
- CVSS 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
- EPSS probability
- 0.15%
- CWE
- CWE-923
- Published
- 2026-06-18
- Last modified
- 2026-08-13
Affected products
- Docker Docker Sandboxes
Weakness type
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