HashiCorp Terraform MCP Server Vulnerabilities: SSRF, Auth Bypass, Credential Reuse (CVE-2026-14869/16496/16498)

Vulnerability Overview HCSEC-2026-23 - Multiple Vulnerabilities Affecting HashiCorp Terraform MCP Server Vulnerability ID: HCSEC-2026-23 Publication Date: July 28, 2026 Affected Versions: terraform-mcp-server 0.2.1 through 1.0.0 (inclusive); fixed in version 1.1.0 Vulnerability Details 1. CVE-2026-14869: Server-Side Request Forgery via Client-Provided Terraform Addresses - Description: A Server-Side Request Forgery (SSRF) vulnerability that allows unauthenticated clients to redirect the server's bearer token to endpoints controlled by an attacker. - Impact: Attackers can send HTTP requests to the streamable-HTTP listener without authentication. 2. CVE-2026-16496: Authorization Bypass in State Mode via Session Credential Caching - Description: In state mode, session credential caching is not bound to the token that created it, allowing other users to utilize the victim's cached Terraform client and bearer token. - Impact: Attackers can access the victim's Terraform organizations, workspaces, variables, and other resources. 3. CVE-2026-16498: Cross-Tenant Credential Reuse in Stateless Mode - Description: In stateless mode, the MCP library does not assign unique session identifiers to requests, leading to the reuse of credentials across different tenants. - Impact: Attackers can use other tenants' credentials for subsequent requests. Impact Scope Affected Modes: - CVE-2026-14869: Affects only deployments using the streamable-HTTP mode. - CVE-2026-16496: Affects only deployments using state mode. - CVE-2026-16498: Affects only deployments using stateless mode. Remediation Upgrade Version: Upgrade to terraform-mcp-server 1.1.0. Mitigations: - For users unable to upgrade immediately, restrict access to the streamable-HTTP listener to trusted users only. - Treat MCP session IDs as sensitive values. Acknowledgments Reporter: CVE-2026-16496 was reported by Juan Pablo Martinez Kuhn of Coinspect. Internal Findings: CVE-2026-14869 and CVE-2026-16498 were discovered by the internal security team. Related Links Migration Guide: View Migration Guide Security Information: HashiCorp Security Page --- Related Topics Terraform vulnerability for version 1.5.7 & 1.7.5 HCSEC-2026-17 - Terraform Enterprise vulnerable to arbitrary file read HCSEC-2021-25 - Terraform Enterprise Configuration Versions API Discloses Sensitive URL HCSEC-2021-18 - Terraform Enterprise Allowed Privilege Escalation Via Run Token HCSEC-2022-06 - Terraform Enterprise May Capture Sensitive Data In Logs --- Summary This advisory covers multiple security issues primarily affecting different operational modes of the HashiCorp Terraform MCP Server. Users are advised to upgrade to version 1.1.0 as soon as possible to resolve these issues. For users unable to upgrade immediately, mitigating measures such as restricting access and protecting sensitive information should be implemented.

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HashiCorp Terraform MCP Server Vulnerabilities: SSRF, Auth Bypass, Credential Reuse (CVE-2026-14869/16496/16498)