CVE-2026-55887: docker mcp-gateway · Argument Injection
Affects docker mcp-gatewaySource CVE Database V5
Not known to be exploited · CVSS 8.7 High : upgrade to 0.42.2 soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-09-15.
- Patch
- Available – fixed in 0.42.2
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade docker mcp-gateway to 0.42.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| dockermcp-gateway | Affected
| Fixed in
|
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.
Reports on CVE-2026-55887
References
- github.com/docker/mcp-gateway/security/advisories/GHSA-r2xf-7jw5-pjg6 (opens in a new tab)
- github.com/docker/mcp-gateway/pull/498 (opens in a new tab)
- github.com/docker/mcp-gateway/commit/306d2d94a3b526f43281313321bf784f2d46a7fe (opens in a new tab)
- github.com/docker/mcp-gateway/commit/439b2200d9e26a4ff414aeb043785df45a78422b (opens in a new tab)
- github.com/docker/mcp-gateway/releases/tag/v0.42.2 (opens in a new tab)