Cyber Resilience

CVE-2026-59565

Published
24 August 2026
Modified
12 October 2026
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0048 39th percentile
Risk Priority 64 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-59565 is a high-severity Improper Handling of Values (CWE-229) vulnerability in Zscaler Client Connector (inferred from references). Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 39th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

A remotely exploitable buffer overflow bug can cause a local and kernel denial-of-service attack on affected versions of Zscaler Client Connector on Windows.

CWE(s)
CWE-229

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
T1687 Exploitation for Defense Impairment Defense Impairment
Adversaries may exploit vulnerabilities in security software, infrastructure, or defensive components to degrade, disable, or otherwise continue to impair their ability to prevent, detect, or respond to malicious activity.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-20268Shared CWE-229
CVE-2024-20431Shared CWE-229
CVE-2024-39531Shared CWE-229
CVE-2024-29460Shared CWE-229
CVE-2024-0607Shared CWE-229
CVE-2025-7964Shared CWE-229
CVE-2026-59566Shared CWE-229
CVE-2024-30800Shared CWE-229
CVE-2025-31648Shared CWE-229
CVE-2025-59032Shared CWE-229

Affected Assets

Zscaler
Client Connector
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation directly enforces correct handling of parameter counts and defined values before processing occurs.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 partial match
blocks

Secure SDLC practices directly require proper input validation and parameter handling to prevent this weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.6.6 Confidentiality or non-disclosure agreements partial match
removes
A.8.19 Installation of software on operational systems partial match
removes
A.8.25 Secure development life cycle partial match
blocks

Secure development lifecycle includes input validation and parameter handling requirements that reduce missing-value errors.

A.8.26 Application security requirements partial match
blocks

A.8.26 requires identifying and specifying requirements (incl. input validation, resilience against SQLi/buffer overflows, integrity checks) that can address improper value handling during development, but this is only a minority slice of CWE-229's broad class of value-count/undefined cases across all input and parameter sites.

A.8.27 Secure system architecture and engineering principles partial match
blocks

A.8.27 mandates security-by-design principles (e.g. distrust input, least privilege, fail securely, data validation/sanitization) and design reviews that can stop improper value handling from reaching production in many cases, but leaves a bounded remainder (e.g. legacy code, outsourced development where principles are only contractually required, or incomplete application of the full set of principles).

A.8.28 Secure coding partial match
prevents

Secure coding standards mandate proper handling of missing or undefined parameters, directly addressing this weakness.

References