HMAC Confirmation Token Unbinding in zscaler-mcp-server (CVE-2026-59563) | HOL Guard CVE

Medium · CVSS 4.6CVE-2026-59563

HMAC Confirmation Token Unbinding in zscaler-mcp-server

Answer in brief

CVE-2026-59563 records a Medium severity (CVSS 4.6) vulnerability in HMAC Confirmation Token Unbinding in zscaler-mcp-server. The current sources do not mark it as known exploited. The current feed maps Zscaler/zscaler-mcp-server (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 28, 2026Updated Sep 28, 2026Source checked Sep 28, 2026First seen by HOL Sep 28, 2026Material review Sep 28, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.6
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 4.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Zscaler/zscaler-mcp-server (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Zscaler/zscaler-mcp-servergeneric	>=0.7.0 <0.7.2	0.7.2

Recommended response

Check inventory. Check lockfiles and deployed manifests for Zscaler/zscaler-mcp-server.
Review the reported fix. Update Zscaler/zscaler-mcp-server to 0.7.2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 28, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.