CVE-2026-59563: HMAC Confirmation Token Unbinding in zscaler-mcp-server

Published Sep 28, 2026

Updated

Zscaler MCP Server versions 0.7.0 and 0.7.1 has an issue where HMAC confirmation tokens were not bound to the target resource identifier, allowing an MCP client or agent to replay a token generated for one resource to affect another resource of the same type. This issue is fixed in version 0.7.2.

Affected Software

1 affected component

Zscaler zscaler-mcp-server=0.7.0, =0.7.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade zscaler-mcp-server to a version that resolves this vulnerability.
Fixed in 0.7.2

Event History

Sep 28, 2026

CVE Published

via MITRE·12:54 PM

Data Sourced

via MITRE·12:54 PM

DescriptionSeverityWeakness

Data Sourced

via NVD·01:17 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Who can exploit this issue?

An MCP client or agent that can obtain a valid HMAC confirmation token can replay it against a different resource of the same type. Exploitation also requires user interaction and low-level privileges.

Which deployments are affected and what version fixes the issue?

Zscaler MCP Server versions 0.7.0 and 0.7.1 are affected. The issue is fixed in version 0.7.2.

What can be done until the server is upgraded?

The provided information does not specify a workaround. Limit access to MCP clients and agents that can generate or use confirmation tokens until upgrading to version 0.7.2.