CVE-2026-55887
MCP Gateway
- Severity
- High
- Published
- September 15, 2026
- Last modified
- September 30, 2026
MCP Gateway allows easy and secure running and deployment of MCP servers. From 0.21.0 until 0.42.2, Docker MCP Gateway YAML-unmarshalled the attacker-controlled io.docker.server.metadata OCI image label into the broad catalog.Server structure for direct docker:// references and catalog snapshot imports in pkg/oci/self_contained.go and pkg/workingset/workingset.go. Runtime-shaping fields including Volumes, User, and ExtraHosts were then appended to the docker run argument vector without an origin allowlist, allowing a malicious image author to request host filesystem or Docker socket mounts and UID 0 execution when a victim selected or pulled the image. This container-creation-time boundary bypass can execute arbitrary code on the host and is not prevented by no-new-privileges because no in-container privilege escalation is required. This issue is fixed in version 0.42.2.
CVSS vector CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X