MCP Gateway Vulnerability in Docker
CVE-2026-55887

8.7HIGH

Key Information:

Vendor

Docker

Status
Mcp-gateway
Vendor
CVE Published:
15 September 2026

What is CVE-2026-55887?

The MCP Gateway, utilized for the deployment of MCP servers, has a significant vulnerability that allows attackers to manipulate Docker images. Versions 0.21.0 through 0.42.2 are susceptible due to improper handling of the attacker-controlled 'io.docker.server.metadata' OCI image label. This flaw permits runtime-shaping fields like Volumes, User, and ExtraHosts to be appended without an origin allowlist. Consequently, a malicious actor can execute arbitrary code on the host machine, leading to unauthorized access to the filesystem and Docker socket mounts. This issue has been resolved in version 0.42.2, emphasizing the importance of keeping software updated for security.

Affected Version(s)

mcp-gateway >= 0.21.0, < 0.42.2

References

https://github.com/docker/mcp-gateway/security/advisories...
x_refsource_CONFIRM
https://github.com/docker/mcp-gateway/pull/498
x_refsource_MISC
https://github.com/docker/mcp-gateway/commit/306d2d94a3b5...
x_refsource_MISC

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.