CVE-2026-39884CWE-88

MCP Server Kubernetes has Argument Injection in its port_forward tool via space-splitting

High · published April 14, 2026

CVSS v3.1
8.3
EPSS
0%
Percentile
34.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.3 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
CVSS v4.0
Not supplied
EPSS
0.00416 · 34.9th percentile
Weakness
CWE-88 · Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
Published
2026-04-14T23:25Z
EPSS history
Timeline
  • 14 APR 23:25Z
    MCP Server Kubernetes has Argument Injection in its port_forward tool via space-splitting
    cvelistv5