# CVE-2026-59563: Zscaler MCP Server HMAC token replay vulnerability

Source: https://junglewise.ai/threats/cve-2026-59563-zscaler-mcp-server-versions-0-7-0-and-0-7-1-has-an-issue-where  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-28. Updated: 2026-09-28  
License: CC BY 4.0 with a link back

CVE-2026-59563 · Severity: medium · CVSS 4.6 · Published 2026-09-28

Zscaler MCP Server is a configuration and policy server that manages access and security settings across cloud platforms. Versions 0.7.0 and 0.7.1 contain a flaw where HMAC confirmation tokens used to authorize operations are not uniquely tied to specific resources, allowing an attacker to replay a token from one resource to modify a different resource of the same type. This could enable unauthorized changes to security policies or configurations.

Vendors: [Zscaler](https://junglewise.ai/threats/vendors/zscaler).

## Quick answers

**Is CVE-2026-59563 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59563 being exploited in the wild.

**How severe is CVE-2026-59563?** Medium severity, with a CVSS score of 4.6, published 28 September 2026.

**Which products and versions are affected?** Zscaler MCP Server 0.7.0, 0.7.1.

**Is there a fix for CVE-2026-59563?** A patch was published on 2026-03-31: Fix merged in version 0.7.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-59563 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-59563?** Check whether you run Zscaler MCP Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an improper cryptographic validation issue (CWE-345) where HMAC confirmation tokens lack binding to target resource identifiers. Delete operations across ZPA, ZIA, and ZTW modules passed empty parameters to confirmation checks, creating fungible tokens replayable across different resources. The fix in version 0.7.2 includes the specific resource identifier in the HMAC payload for all operations, preventing cross-resource token replay attacks.

## Affected products

- Zscaler MCP Server 0.7.0, 0.7.1

## Timeline

- 2026-09-28: disclosed
- 2026-03-31: patched: Fix merged in version 0.7.2

## References

- [https://github.com/zscaler/zscaler-mcp-server/pull/41](https://github.com/zscaler/zscaler-mcp-server/pull/41)