CVE-2026-12112: Foreman MCP Server RCE Vulnerability

CVE-2026-12112 Overview

A session management flaw in the foreman-mcp-server allows local attackers to hijack active administrative sessions. The Model Context Protocol (MCP) Server improperly caches authenticated client connections and trusts non-secret session identifiers without re-validating authentication tokens. The server also writes newly created session IDs to standard logs, exposing them to any user with log read access. An attacker who obtains a session ID can impersonate an authenticated administrator and execute commands across the managed Foreman infrastructure. This issue maps to [CWE-287] Improper Authentication.

Critical Impact
Local attackers with low privileges can hijack administrative MCP sessions, leading to privilege escalation and infrastructure-wide code execution across Foreman-managed systems.

Affected Products

Red Hat foreman-mcp-server
Foreman MCP Server deployments distributed via RHSA-2026:28438
Foreman infrastructure managed through affected MCP Server instances

Discovery Timeline

2026-06-23 - CVE CVE-2026-12112 published to NVD
2026-06-25 - Last updated in NVD database

Technical Details for CVE-2026-12112

Vulnerability Analysis

The foreman-mcp-server exposes a Model Context Protocol interface used to broker administrative actions against Foreman-managed infrastructure. The server maintains a cache of authenticated client connections keyed by session identifier. When a request arrives with a known session ID, the server reuses the cached authenticated context without re-validating the bearer token or any cryptographic proof of possession.

Session IDs are not treated as secrets. They are written verbatim to standard application logs as part of normal connection accounting. Any local user, container sidecar, or log forwarder with read access to those logs can extract a valid session ID. Replaying that identifier against the MCP endpoint binds the attacker to the cached administrative session.

Successful exploitation grants the attacker the privileges of the hijacked session. Because Foreman administrators typically orchestrate provisioning, configuration management, and remote command execution, a hijacked session can be pivoted into code execution across every host managed by the Foreman instance.

Root Cause

The root cause is twofold. The MCP Server treats the session ID as both an identifier and an authenticator, violating the principle that authentication must be re-verified per request using a secret credential. Logging the session ID at creation time compounds the issue by widening the set of principals that can observe it.

Attack Vector

The attack requires local access with low privileges, no user interaction, and an active administrative session on the target MCP Server. The attacker reads the session ID from logs, then issues MCP requests carrying that identifier to inherit the cached authentication state.

The vulnerability mechanism is described in prose because no verified proof-of-concept code is published. See the Red Hat CVE Details and Red Hat Bug Report #2488031 for vendor technical analysis.

Detection Methods for CVE-2026-12112

Indicators of Compromise

Session IDs from foreman-mcp-server logs appearing in requests originating from unexpected local users or processes.
MCP administrative actions executed under a session whose source process or user does not match the original authenticated client.
Unexpected Foreman remote execution jobs, host provisioning, or configuration changes following local log access events.

Detection Strategies

Correlate foreman-mcp-server log read events with subsequent MCP API calls from non-administrative local accounts.
Alert on reuse of the same session ID by distinct local UIDs, process trees, or network sockets.
Baseline normal MCP administrative activity and flag deviations in command volume, target host count, or off-hours execution.

Monitoring Recommendations

Restrict and audit read access to all logs that may contain MCP session identifiers.
Forward foreman-mcp-server logs to a centralized analytics platform for cross-host session reuse detection.
Monitor Foreman remote execution and API audit trails for actions initiated through the MCP Server, especially mass-host operations.

How to Mitigate CVE-2026-12112

Immediate Actions Required

Apply the Red Hat security update referenced in RHSA-2026:28438 to all foreman-mcp-server instances.
Invalidate all existing MCP sessions and force administrators to re-authenticate after patching.
Rotate any authentication tokens or API credentials that may have been exposed through session hijack.
Restrict local shell and log access on hosts running foreman-mcp-server to a minimum set of trusted operators.

Patch Information

Red Hat has released fixed packages through RHSA-2026:28438. The update modifies the MCP Server to re-validate authentication tokens on each request and stops logging session identifiers in plaintext. Consult the Red Hat CVE Details page for the complete list of fixed component versions.

Workarounds

Disable the foreman-mcp-server service until the patched packages can be deployed if MCP functionality is not required.
Tighten filesystem permissions on MCP log files and directories so only the service account can read them.
Place the MCP Server behind an authenticating reverse proxy that enforces per-request token validation independent of the cached session.

bash

# Configuration example: restrict log access and disable the service pending patching
sudo systemctl stop foreman-mcp-server
sudo systemctl disable foreman-mcp-server
sudo chmod 600 /var/log/foreman-mcp-server/*.log
sudo chown foreman-mcp:foreman-mcp /var/log/foreman-mcp-server