CVE-2026-59565Network attack vector

Denial of service via remote buffer overflow

Published Aug 24, 2026 · Updated Aug 24, 2026

Buffer overflow in Zscaler Client Connector on Windows allows remote authenticated users to cause endpoint and kernel denial of service. Zscaler identifies the defect only as a remotely triggerable buffer overflow and has not disclosed the affected component, input field, or faulty memory operation. Low-privileged authentication and network reachability are required; affected builds precede the applicable 4.6.0.457, 4.7.0.317, 4.8.0.232, or 4.9.0.372 branch threshold.

CVSS severity8.8
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Zscaler Client Connector on Windows allows remote authenticated users to cause endpoint and kernel denial of service. Zscaler identifies the defect only as a remotely triggerable buffer overflow and has not disclosed the affected component, input field, or faulty memory operation. Low-privileged authentication and network reachability are required; affected builds precede the applicable 4.6.0.457, 4.7.0.317, 4.8.0.232, or 4.9.0.372 branch threshold.

The record

CVE
CVE-2026-59565
Published
Aug 24, 2026
Updated
Aug 24, 2026
Vendor
Zscaler
Product
Zscaler Client Connector
Classifications
CWE-229, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 24, 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 <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 privilegesauthenticated

What is affected?

Zscaler · Zscaler Client Connectorversion=0 <Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372

Published CVSS scores

8.8Zscaler, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-229Improper Handling of Values
T1499Endpoint Denial of Service

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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