{"schemaVersion":3,"id":"CVE-2026-55887","aliases":["GHSA-r2xf-7jw5-pjg6","GO-2026-5604"],"status":"published","duplicateOf":null,"title":null,"description":"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.","dates":{"published":"2026-09-15T15:45:36.420Z","modified":"2026-09-15T18:02:09.186Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":8.7,"severity":"high","version":"4.0","versionLabel":"v4.0","source":"CVE.org","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","computed":false,"selection":"backend-summary"},"metrics":[{"version":"4.0","versionLabel":"v4.0","source":"CVE.org","score":8.7,"severity":"high","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","exploitability":null,"impact":null,"computed":false},{"version":"4.0","versionLabel":"v4.0","source":"OSV · 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Neutralization of Argument Delimiters in a Command ('Argument Injection')","description":"The product constructs a string for a command to be executed by a separate component\nin another control sphere, but it does not properly delimit the\nintended arguments, options, or switches within that command string.","type":"weakness","status":"Draft","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/88.html"}],"affected":[{"vendor":"docker","product":"mcp-gateway","name":"mcp-gateway","label":"mcp-gateway","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 0.21.0, < 0.42.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 0.21.0, < 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