EUVD-2026-49940
GHSA-4crw-p722-vr7h
Severity by source
AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
Network-reachable HTTP transport (AV:N) but requires stealing a victim session ID (AC:H) with no attacker account (PR:N); cross-user credential misuse changes scope (S:C) with high confidentiality/integrity over managed infrastructure.
Primary rating from Vendor (HashiCorp).
CVSS VectorVendor: HashiCorp
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
Lifecycle Timeline
3DescriptionCVE.org
The terraform-mcp-server before version 1.1.0 is vulnerable to an authorization bypass in the streamable-HTTP stateful transport mode that may allow a user who obtains another user's MCP session ID to have their tool calls executed using that user's Terraform credentials. This vulnerability, CVE-2026-16496, is fixed in terraform-mcp-server 1.1.0.
Articles & Coverage 1
AnalysisAI
Authorization bypass in HashiCorp's terraform-mcp-server (versions 0.3.0 through 1.0.x) lets an attacker who obtains another user's MCP session identifier execute their own tool calls under the victim's Terraform credentials when the server runs in streamable-HTTP stateful transport mode. Rooted in a session fixation weakness (CWE-384), the flaw carries a CVSS 8.9 with a scope change, meaning cross-user credential misuse against managed infrastructure. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that terraform-mcp-server (version 0.3.0 to <1.1.0) be running specifically in the streamable-HTTP stateful transport mode, and that the attacker first obtain a valid MCP session ID belonging to another user. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals are mixed and should be read together. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | In a shared terraform-mcp-server deployment running the streamable-HTTP stateful transport, an attacker captures or reuses another user's MCP session ID (for example via network interception, logs, or a leaked token). Replaying that session ID, the attacker issues Terraform tool calls that execute with the victim's Terraform credentials, potentially reading state, modifying infrastructure, or exfiltrating secrets. … |
| Remediation | Vendor-released patch: 1.1.0 - upgrade terraform-mcp-server to 1.1.0 or later, which fixes CVE-2026-16496 as described in HashiCorp HCSEC-2026-23 (https://discuss.hashicorp.com/t/hcsec-2026-23-multiple-vulnerabilities-impacting-hashicorp-terraform-mcp-server/77606). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all terraform-mcp-server deployments and identify which instances run in streamable-HTTP stateful transport mode-these are your immediate priority. …
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External POC / Exploit Code
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