CVE-2026-59567 Overview
CVE-2026-59567 describes multiple vulnerabilities in Zscaler Client Connector that enable local privilege escalation. An unprivileged local user can execute arbitrary code in a privileged context on affected installations. The weakness is categorized as improper handling of insufficient permissions or privileges [CWE-280].
The scope-changed CVSS vector indicates that successful exploitation impacts resources beyond the vulnerable component. Attackers who already hold low-privilege access on an endpoint can leverage the flaw to obtain full control over confidentiality, integrity, and availability of the host.
Critical Impact
A local attacker with low privileges can execute arbitrary code as a privileged user, resulting in full endpoint compromise across confidentiality, integrity, and availability.
Affected Products
- Zscaler Client Connector (affected versions per vendor advisory)
- Windows endpoints running vulnerable Zscaler Client Connector builds
- See the Zscaler Client Connector Release Summary for the fixed version list
Discovery Timeline
- 2026-08-24 - CVE-2026-59567 published to the National Vulnerability Database (NVD)
- 2026-08-25 - Last updated in NVD database
Technical Details for CVE-2026-59567
Vulnerability Analysis
CVE-2026-59567 aggregates multiple local privilege escalation defects in Zscaler Client Connector. The endpoint agent runs privileged service components that interact with unprivileged user-mode processes. When these boundaries are not enforced correctly, a low-privileged user can influence privileged operations and execute code in the security context of the service.
The classification under [CWE-280] indicates improper handling of insufficient permissions or privileges. In practice, this class of defect surfaces when a privileged component trusts input, file paths, named pipes, or interprocess communication channels that an unprivileged user can control or manipulate.
The scope change flag in the CVSS vector reflects that the compromise crosses a security boundary. Code executed via the exploit does not remain within the low-privilege session; it executes with the elevated rights of the Client Connector service.
Root Cause
The root cause aligns with [CWE-280]: privileged code paths in Zscaler Client Connector do not adequately validate the privileges, ownership, or integrity of resources supplied or influenced by local users. Zscaler has not published low-level technical details in the release summary. Refer to the Zscaler Client Connector Release Summary for authoritative advisory content.
Attack Vector
Exploitation requires local access and low-level authenticated privileges. No user interaction is required. An attacker with a standard interactive session, a Remote Desktop Protocol (RDP) session, or code execution as a low-privileged service can target the vulnerable Client Connector components. Successful exploitation yields arbitrary code execution in a privileged context, enabling credential theft, security tooling tampering, and persistence.
No public proof-of-concept exploit is listed in Exploit-DB, and CVE-2026-59567 is not tracked on the CISA Known Exploited Vulnerabilities (KEV) catalog at time of publication.
Detection Methods for CVE-2026-59567
Indicators of Compromise
- Unexpected child processes spawned by Zscaler Client Connector service binaries running as NT AUTHORITY\SYSTEM.
- New or modified files, DLLs, or scheduled tasks in Zscaler installation directories written by non-administrative users.
- Anomalous named-pipe or local IPC connections from standard user processes to Zscaler service endpoints.
- Local account privilege changes or new administrative accounts created shortly after Client Connector activity.
Detection Strategies
- Monitor process lineage for privileged Zscaler service processes spawning shells, script interpreters, or LOLBins.
- Alert on writes to Zscaler program directories originating from non-SYSTEM, non-installer processes.
- Correlate low-privilege user sessions with subsequent SYSTEM-context command execution on the same host.
Monitoring Recommendations
- Ingest endpoint process, file, and IPC telemetry into a centralized data lake for retrospective hunting.
- Track Client Connector version inventory across the fleet to identify hosts still running vulnerable builds.
- Enable tamper-protection alerts on the Client Connector service to detect unauthorized stop, restart, or binary replacement attempts.
How to Mitigate CVE-2026-59567
Immediate Actions Required
- Upgrade Zscaler Client Connector to the fixed version identified in the Zscaler Client Connector Release Summary.
- Inventory all endpoints running Client Connector and prioritize multi-user systems, jump hosts, and VDI images.
- Restrict local logon and interactive session rights on sensitive hosts to reduce the pool of accounts capable of exploitation.
- Verify that endpoint protection and audit logging are active and forwarding to a central SIEM.
Patch Information
Zscaler has released fixed versions of Client Connector that remediate CVE-2026-59567. The vendor's release summary is the authoritative source for exact fixed builds and rollout guidance. Consult the Zscaler Client Connector Release Summary and deploy the update through your standard Client Connector distribution channel.
Workarounds
- No vendor-supplied workaround replaces patching. Apply the vendor update as the primary remediation.
- Enforce least privilege on endpoints and remove unnecessary local administrator rights.
- Limit interactive and remote logon rights on shared systems until patching is complete.
- Monitor Client Connector processes for anomalous child process creation and file writes as a compensating control.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
