CVE-2026-55887Published

MCP Gateway: Argument injection via OCI image label YAML in Docker MCP Gateway

Collected exploitation and prediction evidence

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2026-55887

Published

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.

Source published: 15 Sep 2026 15:45:36 UTC
Source modified: 15 Sep 2026 18:02:09 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 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

euvd · EUVD-2026-78684

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Sep 15, 2026, 3:45:36 PM

dateUpdated: Sep 15, 2026, 6:02:09 PM

Source published: Sep 15, 2026, 3:45:36 PM (timezone not stated)
Source modified: Sep 15, 2026, 6:02:09 PM (timezone not stated)
Observed here: 11 Nov 2026 14:05:12 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 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

nvd · CVE-2026-55887

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-88

Original publisher date fields

published: 2026-09-15T16:17:16.667

lastModified: 2026-09-30T17:51:56.193

Source published: 15 Sep 2026 16:17:16 UTC
Source modified: 30 Sep 2026 17:51:56 UTC
Observed here: 25 Oct 2026 14:19:05 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 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/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

osv · GHSA-r2xf-7jw5-pjg6

Published

## 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

Source published: 18 Jun 2026 13:05:06 UTC
Source modified: 25 Jun 2026 23:11:30 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · 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

Publisher rating · HIGH

osv · GO-2026-5604

Published

Docker MCP Gateway: Argument injection via OCI image label YAML in github.com/docker/mcp-gateway

Source published: 25 Jun 2026 22:34:34 UTC
Source modified: 25 Jun 2026 23:01:35 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.