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Docker CVE-2026-55887

| EUVDEUVD-2026-78684 HIGH
Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') (CWE-88)
2026-06-18 https://github.com/docker/mcp-gateway GHSA-r2xf-7jw5-pjg6
8.7
CVSS 4.0 · Vendor: https://github.com/docker/mcp-gateway
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Argument sanitization
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv2 – Sep 15, 2026

Argument injection in Docker MCP Gateway 0.21.0 through 0.42.1 allows an attacker who controls an OCI image — one the victim references via a docker:// URI or that the victim's catalog snapshots — to smuggle arbitrary flags into the docker run command line assembled by the gateway, binding the host root filesystem into the container and running as UID 0. Because the injected arguments (for example -v /:/host, -u root, and a mounted /var/run/docker.sock) take effect at container-creation time, the gateway's --security-opt no-new-privileges setting offers no protection and the attacker obtains root-level code execution on the gateway host. Vendor-released patch: 0.42.2; no public exploit code identified at time of analysis and no CISA KEV confirmation of active exploitation.

Earlier versions of this analysis (1)
v1 Jun 18, 2026 - 14:02

Arbitrary code execution as root on the host running Docker MCP Gateway via argument injection in the docker run command line. A malicious OCI image author can craft an io.docker.server.metadata label that YAML-unmarshals into runtime-shaping fields of the catalog.Server struct, causing the gateway to append attacker-chosen flags like -v /:/host and -u root when launching the MCP server container. No public exploit identified at time of analysis, but the upstream advisory describes a full exploitation path.

Affected VersionsENISA

mcp-gateway 0.21.0, < 0.42.2

Affected Packages

go github.com/docker/mcp-gateway fix: 0.42.2
euvd mcp_gateway_0_21_0 fix: 0.42.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in go, euvd

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (https://github.com/docker/mcp-gateway) PRIMARY 8.7 HIGH
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
vuln.today AI 8.3 HIGH

Image is fetched over the network (AV:N) but requires the victim to reference an attacker-controlled image (UI:R) and supply-chain positioning (AC:H); no gateway auth needed (PR:N); container-host boundary crossed (S:C) with full host compromise.

3.1 AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (https://github.com/docker/mcp-gateway).

CVSS VectorVendor: https://github.com/docker/mcp-gateway

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
High
Subsequent system: Confidentiality
High
Subsequent system: Integrity
High
Subsequent system: Availability
High

Lifecycle Timeline

2
Analysis Updated
Sep 15, 2026 - 16:33 vuln.today
v2 - CVSS changed
CVSS changed
Sep 15, 2026 - 16:22 NVD
8.7 (HIGH)

DescriptionCVE.org

Summary

A maliciously crafted OCI image label can inject arbitrary arguments into the docker run command line constructed by the MCP Gateway. An attacker who controls an image that the victim references via docker://, or that the victim's catalog pulls a snapshot from, can mount the host filesystem, run as UID 0, and execute arbitrary code on the host.

Details

The io.docker.server.metadata OCI image label is YAML-unmarshalled directly into the wide catalog.Server struct, which carries runtime-shaping fields (Volumes, User, Command, ExtraHosts, AllowHosts, DisableNetwork, Env, Remote, SSEEndpoint, OAuth,Secrets, LongLived, Policy) alongside descriptive fields. Every runtime field carries a YAML tag, so the unmarshal mass-assigns from the attacker-controlled label content; only Image is overwritten afterwards. The gateway's container-launch code then appends those fields verbatim as docker run flags (-v, -u, --add-host) with no allowlist or origin check, and execs docker with the resulting argv.

Impact

A malicious image author can achieve arbitrary code execution as UID 0 on the host of a victim running an affected version of MCP Gateway. Attacker-injected -v /:/host, -u root, and -v /var/run/docker.sock:/var/run/docker.sock arguments reach the docker run invocation that launches the MCP server container, giving the attacker full host filesystem access and root execution. The container/host trust boundary is bypassed at container-creation time, so the --security-opt no-new-privileges flag the gateway applies provides no protection: no in-container privilege escalation is needed.

Patches

The OCI image-label parser now only populates descriptive fields from the image label, which excludes fields that control the container runtime.

Credit

This issue was reported by Jabr Al-Otaibi @ DarkCov working with TrendAI Zero Day Initiative

Executive ViewAI

Why It Matters

Docker MCP Gateway contains a vulnerability that allows attackers with control over container images to gain complete access to affected host systems, compromising all applications and data running on them. Organizations using this gateway with externally-sourced containers face significant risk of infrastructure compromise.

Recommended Action

Within 24 hours: Inventory all Docker MCP Gateway deployments and identify which systems process untrusted or externally-sourced container images. Within 7 days: Implement image source restrictions to allow only pre-vetted and internally-managed containers, and isolate vulnerable systems from production networks. Within 30 days: Monitor the upstream project for security patch availability and establish upgrade procedures once released.

Business Impact: Severe
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Restrict container image sources to internal registries or explicitly approved external sources only; (2) Implement network segmentation to prevent compromised systems from accessing critical infrastructure; (3) Apply strict container runtime policies (AppArmor/SELinux) to limit privilege escalation; (4) Enable comprehensive monitoring and alerting on container execution and label parsing activities.

Threat Intelligence Overview

EPSS Score
0.2%
Top 90% exploitable
Threat Intel
1
1 source
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact
Very High

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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Vendor StatusVendor

SUSE

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