CVE-2026-12539

Docker Sandboxes ICMP egress restriction bypass after daemon restart

State: Published
Severity: 5.1 Medium
Published: Jun 18, 2026
Updated: Aug 13, 2026
Reserved: Jun 17, 2026

Description

Docker Sandboxes (sbx) blocks ICMP egress with an authorizer applied only at network-creation time, and does not re-apply it to networks rebuilt from disk when the Docker daemon restarts, so a restart-surviving sandbox forwards ICMP to arbitrary hosts. A workload inside a sandbox, which the threat model treats as untrusted, can therefore defeat the documented ICMP egress block to perform network reconnaissance and exfiltrate data over an ICMP covert channel, regardless of the configured allowlist.

Scores

CVSS	Score	Vector	Source
4.0	5.1 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	Docker

Weaknesses

CWE-923 Improper Restriction of Communication Channel to Intended Endpoints
CWE-665 Improper Initialization

Affected Products

Product	Versions
Docker SandboxesDocker	0.14.0 to before 0.33.0Affected

References

https://docs.docker.com/ai/sandboxes/product
https://github.com/docker/sbx-releases/releases/tag/v0.33.0release-notes

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