# CVE-2026-59564: Zscaler Client Connector authentication bypass

Source: https://junglewise.ai/threats/cve-2026-59564-zscaler-client-connector-authentication-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-24. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-59564 · Severity: critical · CVSS 9.1 · Published 2026-08-24

Zscaler Client Connector is a software agent that manages secure network access for remote employees. An authentication bypass vulnerability in communications between the client and its portal could allow an attacker to impersonate legitimate users or gain unauthorized access to protected resources, potentially compromising employee data and network security.

Technologies: [Zscaler Client Connector](https://junglewise.ai/threats/technologies/client-connector). Vendors: [Zscaler](https://junglewise.ai/threats/vendors/zscaler).

## Quick answers

**Is CVE-2026-59564 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59564 being exploited in the wild.

**How severe is CVE-2026-59564?** Critical severity, with a CVSS score of 9.1, published 24 August 2026.

**Which products and versions are affected?** Zscaler Client Connector <UNKNOWN>.

**Is there a fix for CVE-2026-59564?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-59564 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-59564?** Check whether you run Zscaler Client Connector 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

An authentication bypass vulnerability exists in the communications protocol between affected versions of Zscaler Client Connector and the Zscaler Client Connector Portal. The vulnerability allows attackers to circumvent authentication mechanisms without valid credentials. The exact attack vector and preconditions are not detailed in the available advisory text, but the critical severity rating suggests an easily exploitable flaw with significant impact. Patches are available through Zscaler client connector releases.

## Affected products

- Zscaler Client Connector <UNKNOWN>

## Timeline

- 2026-08-24: disclosed

## References

- [https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2026](https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2026)

## Related threats

- [Zscaler Client Connector peer app access control bypass](https://junglewise.ai/threats/cve-2026-59570-zscaler-client-connector-peer-app-access-control-bypass)
- [Zscaler Client Connector improper input validation on Android and ChromeOS](https://junglewise.ai/threats/cve-2026-59569-zscaler-client-connector-improper-input-validation-on-android-and)
- [Zscaler Client Connector race condition in ZPA tunnel handler](https://junglewise.ai/threats/cve-2026-25687-zscaler-client-connector-race-condition-in-zpa-tunnel-handler)
- [Zscaler Client Connector remote code execution](https://junglewise.ai/threats/cve-2026-59568-zscaler-client-connector-remote-code-execution)
- [Zscaler Client Connector local privilege escalation](https://junglewise.ai/threats/cve-2026-59567-zscaler-client-connector-local-privilege-escalation)