# CVE-2026-55887

## Summary

- **CVE ID:** CVE-2026-55887
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-88
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## 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.

## Affected Products

- docker — mcp-gateway (>= 0.21.0, < 0.42.2)

## References

- [CNA](https://github.com/docker/mcp-gateway/security/advisories/GHSA-r2xf-7jw5-pjg6)
- [CNA](https://github.com/docker/mcp-gateway/pull/498)
- [CNA](https://github.com/docker/mcp-gateway/commit/306d2d94a3b526f43281313321bf784f2d46a7fe)
- [CNA](https://github.com/docker/mcp-gateway/commit/439b2200d9e26a4ff414aeb043785df45a78422b)
- [CNA](https://github.com/docker/mcp-gateway/releases/tag/v0.42.2)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.20%
- **EPSS Percentile:** 9.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._