How severe is CVE-2026-59564?

CVE-2026-59564 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-59564 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-59564?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-59564 published?

CVE-2026-59564 was published on 2026-08-24 and last updated on 2026-08-28.

CVE-2026-59564

CVE-2026-59564 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-304.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-304
Published: 2026-08-24
Last modified: 2026-08-28

Description

An authentication bypass issue exists in communications between affected versions of the Zscaler Client Connector and the Zscaler Client Connector Portal.

Frequently asked questions

What is CVE-2026-59564?: An authentication bypass issue exists in communications between affected versions of the Zscaler Client Connector and the Zscaler Client Connector Portal.
How severe is CVE-2026-59564?: CVE-2026-59564 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-59564 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-59564?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-59564 published?: CVE-2026-59564 was published on 2026-08-24 and last updated on 2026-08-28.

References

https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2026

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