What is CVE-2026-59563?

CVE-2026-59563 is a medium-severity vulnerability in Zscaler Zscaler-Mcp-Server, classified under Authentication Bypass by Primary Weakness. CVSS score: 4.6/10. Published 2026-09-28.

How severe is CVE-2026-59563?

Medium severity. CVSS v3 base score is 4.6 out of 10.

Vulnerability in Zscaler Zscaler-Mcp-Server

CVE-2026-59563

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.

Published 2026-09-28 · last modified 2026-09-28.

CVSS v3 metric

CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Zscaler Zscaler-Mcp-Server

Weakness classification (CWE)

CWE-305 — Authentication Bypass by Primary Weakness

References

github.com/zscaler/zscaler-mcp-server/pull/41

Frequently asked questions

What is CVE-2026-59563?: CVE-2026-59563 is a medium-severity vulnerability in Zscaler Zscaler-Mcp-Server, classified under Authentication Bypass by Primary Weakness. CVSS score: 4.6/10. Published 2026-09-28.
How severe is CVE-2026-59563?: Medium severity. CVSS v3 base score is 4.6 out of 10.