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CVE-2026-39884— MCP Server Kubernetes has Argument Injection in its port_forward tool via space-splitting

Quick assessment

Affected
Flux159 mcp-server-kubernetes
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MCP Server Kubernetes是Suyog Sonwalkar个人开发者的一个用于kubernetes管理的MCP服务器。 MCP Server Kubernetes 3.4.0及之前版本存在安全漏洞，该漏洞源于port_forward工具中参数注入问题，可能导致暴露内部Kubernetes服务、跨命名空间目标定位或通过AI代理进行间接利用。

CVSS 8.3 · High EPSS 0.42% · P34
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I. Basic Information for CVE-2026-39884

Vulnerability Information
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Vulnerability Title
MCP Server Kubernetes has Argument Injection in its port_forward tool via space-splitting
Source: CVE Program / CVE List V5
Vulnerability Description
mcp-server-kubernetes is a Model Context Protocol server for Kubernetes cluster management. Versions 3.4.0 and prior contain an argument injection vulnerability in the port_forward tool in src/tools/port_forward.ts, where a kubectl command is constructed via string concatenation with user-controlled input and then naively split on spaces before being passed to spawn(). Unlike all other tools in the codebase which correctly use array-based argument passing with execFileSync(), port_forward treats every space in user-controlled fields (namespace, resourceType, resourceName, localPort, targetPort) as an argument boundary, allowing an attacker to inject arbitrary kubectl flags. This enables exposure of internal Kubernetes services to the network by injecting --address=0.0.0.0, cross-namespace targeting by injecting additional -n flags, and indirect exploitation via prompt injection against AI agents connected to the MCP server. This issue has been fixed in version 3.5.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
参数注入或修改
Source: CVE Program / CVE List V5
Vulnerability Title
MCP Server Kubernetes 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MCP Server Kubernetes是Suyog Sonwalkar个人开发者的一个用于kubernetes管理的MCP服务器。 MCP Server Kubernetes 3.4.0及之前版本存在安全漏洞，该漏洞源于port_forward工具中参数注入问题，可能导致暴露内部Kubernetes服务、跨命名空间目标定位或通过AI代理进行间接利用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Flux159 mcp-server-kubernetes < 3.5.0 -

II. Public POCs for CVE-2026-39884

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III. Intelligence Information for CVE-2026-39884

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Vendor Advisories for CVE-2026-39884 (1)

IV. Related Vulnerabilities

Same product: mcp-server-kubernetes
Same vendor: Flux159
Same weakness: CWE-88

V. Comments for CVE-2026-39884

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