CVE-2026-16496Network attack vector

Cross-user tool execution via unbound session cache

Published Jul 28, 2026 · Updated Jul 28, 2026

Authorization bypass in HashiCorp Terraform MCP Server before 1.1.0 allows remote authenticated users to execute tools with another user's token. The stateful Streamable HTTP client cache keys entries only by MCP session ID and does not bind cached Terraform clients to the token that created them. Exploitation requires a victim's session ID; stdio and stateless HTTP modes are unaffected, while successful calls inherit the victim token's Terraform permissions.

CVSS severity8.9
High
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in HashiCorp Terraform MCP Server before 1.1.0 allows remote authenticated users to execute tools with another user's token. The stateful Streamable HTTP client cache keys entries only by MCP session ID and does not bind cached Terraform clients to the token that created them. Exploitation requires a victim's session ID; stdio and stateless HTTP modes are unaffected, while successful calls inherit the victim token's Terraform permissions.

The record

CVE
CVE-2026-16496
Published
Jul 28, 2026
Updated
Jul 28, 2026
Vendor
HashiCorp
Product
Terraform MCP Server
Classifications
CWE-384, T1550
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.3.0 <1.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

HashiCorp · Terraform MCP Serverversion=0.3.0 <1.1.0

Published CVSS scores

8.9HashiCorp Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-384Session Fixation
T1550Use Alternate Authentication Material

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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