CVE-2026-12112: Foreman MCP Server Session Hijacking Vulnerability

Technical summary

CVE-2026-12112 is a session management weakness (CWE-287) in the MCP Server component of foreman-mcp-server. The vulnerability arises from three design failures: (1) the server caches authenticated client connections and trusts them on subsequent interactions without re-validating authentication tokens, (2) session identifiers lack cryptographic entropy or are otherwise non-secret, and (3) newly created session IDs are logged to standard output, where they persist in plaintext logs accessible to local system users. This combination allows a local attacker to extract valid session tokens from logs and replay them to impersonate legitimate administrative users without credential re-entry.

Business impact

Successful exploitation grants attackers the ability to assume the identity of system administrators and execute arbitrary code across the infrastructure managed by the affected foreman instance. In a Red Hat Satellite environment, this translates to complete control over patch management, configuration, and lifecycle operations for all registered systems. The risk is particularly acute in multi-tenant or shared-resource scenarios where multiple teams rely on the same foreman deployment, as a single compromised local account can lead to organization-wide infrastructure compromise.

Affected systems

This vulnerability affects Red Hat Satellite and The Foreman (open-source) products that bundle or use the foreman-mcp-server component. Organizations running these tools should inventory instances and determine exposure scope based on local access controls. Verify the exact affected versions against the vendor security advisory, as patch versions vary between Red Hat Satellite and upstream Foreman releases.

Exploitability

The vulnerability requires local system access (indicated by the CVSS vector AV:L), which is a prerequisite limitation. However, once an attacker achieves local access—whether through container escape, compromised host account, or insider threat—exploitation is straightforward: read the plaintext session logs, extract a session ID, and use it to authenticate as an administrator. No user interaction is needed (UI:N), and the attack is deterministic (AC:L). The low barrier to exploitation post-compromise makes this a critical lateral-movement and privilege-escalation vector.

Remediation

Apply the security patch released by your vendor (Red Hat Satellite or upstream Foreman). The fix should address session validation by re-authenticating tokens on each request, implementing cryptographically secure session identifiers, and stopping the logging of session IDs to standard output. Until patching is complete, implement strict local access controls on systems running foreman-mcp-server, restrict log file permissions to prevent unprivileged users from reading session data, and rotate all administrative credentials as a defensive measure. Consider isolating the MCP Server to a separate network segment if feasible.

Patch guidance

Contact your vendor (Red Hat or The Foreman upstream project) to obtain the patched version. Verify the patch version number in the vendor advisory before deployment. Test the patch in a non-production environment to ensure compatibility with your foreman plugins and automation runbooks. Plan a maintenance window to deploy the patch; session invalidation during the update should be acceptable but should be communicated to stakeholders. After patching, audit session logs and administrative activity for signs of unauthorized access during the vulnerability window.

Detection guidance

Monitor foreman-mcp-server logs for suspicious session activity: look for authentication tokens or session IDs appearing in standard output or system logs, sessions authenticated from unexpected source IPs or users, and administrative actions performed outside normal business hours or by unusual accounts. Implement log aggregation and alerting to flag any session ID patterns in plaintext logs. Check file access logs on systems hosting foreman to detect unauthorized reads of configuration or log files. Network monitoring can help identify lateral movement from compromised hosts toward the foreman server.

Why prioritize this

Although this is a HIGH-severity vulnerability (CVSS 7.8) and not yet on the KEV catalog, the combination of infrastructure-wide impact, local-access prerequisite, and straightforward exploitation in post-compromise scenarios warrants immediate prioritization. Organizations with strict local access controls may classify this as lower risk, but those with permissive container or host security postures should treat it as urgent. The privilege-escalation and code-execution outcomes make this particularly dangerous in CI/CD and infrastructure-automation environments.

Risk score, explained

The CVSS 3.1 score of 7.8 (HIGH) reflects high confidentiality, integrity, and availability impact (C:H, I:H, A:H) once an attacker gains local system access. The attack vector is local (AV:L) and privileges are required (PR:L), which moderates the score somewhat, but the lack of user interaction and the straightforward nature of the exploit path justify the HIGH severity. The scope is unchanged (S:U), meaning the impact is limited to the vulnerable component and systems it manages.

Frequently asked questions