CVE-2026-59564Network attack vector

Unauthenticated portal access via missing authentication step

Published Aug 24, 2026 · Updated Aug 25, 2026

Authentication bypass in Zscaler Client Connector allows remote attackers to access Client Connector Portal communications. The client-to-portal exchange skips a critical authentication step; Zscaler has not disclosed the specific message, endpoint, or validation error. Network access requires no prior privileges or user interaction and permits reading or altering protected communications without reported service interruption.

CVSS severity9.1
Critical
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Zscaler Client Connector allows remote attackers to access Client Connector Portal communications. The client-to-portal exchange skips a critical authentication step; Zscaler has not disclosed the specific message, endpoint, or validation error. Network access requires no prior privileges or user interaction and permits reading or altering protected communications without reported service interruption.

The record

CVE
CVE-2026-59564
Published
Aug 24, 2026
Updated
Aug 25, 2026
Vendor
Zscaler
Product
Zscaler Client Connector
Classifications
CWE-304, CAPEC-115
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <Android: 4.2
  2. Affected versionversion=0 <ChromeOS: 4.2
  3. Affected versionversion=0 <iOS: 4.5.1
  4. Affected versionversion=0 <Linux: 3.7.2.64, 4.2.1.64
  5. Affected versionversion=0 <MacOS: 4.5.2.312, 4.7.0.292, 4.8.0.191
  6. Affected versionversion=0 <Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zscaler · Zscaler Client Connectorversion=0 <Android: 4.2; version=0 <ChromeOS: 4.2; version=0 <iOS: 4.5.1; version=0 <Linux: 3.7.2.64, 4.2.1.64; version=0 <MacOS: 4.5.2.312, 4.7.0.292, 4.8.0.191; version=0 <Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372

Published CVSS scores

9.1ZscalerCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-304Missing Critical Step in Authentication
CAPEC-115Authentication Bypass

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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