Zscaler is widely deployed for enterprise network/security controls; an auth-bypass in its client/portal could let attackers evade central security controls and alter policies broadly.
CVE-2026-59564
Authentication bypass in Zscaler Client Connector <> Portal communications
Is CVE-2026-59564 being exploited?
Not confirmed. CVE-2026-59564 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.30% probability of exploitation in the next 30 days.
How severe is CVE-2026-59564?
CVE-2026-59564 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-59564?
Not known from our data. No patch reference has been recorded for CVE-2026-59564, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-59564 affect?
CVE-2026-59564 affects Zscaler Client Connector, Zscaler Client Connector Portal, Enterprise deployments using Zscaler cloud. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-59564?
Apply vendor patch/mitigations ASAP; restrict portal access, rotate credentials, and monitor logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Auth bypass allows attacker to impersonate client or portal, gain unauthorized management access, change policies, or bypass security controls.
Immediate action required
- affected< Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372
- affected< MacOS: 4.5.2.312, 4.7.0.292, 4.8.0.191
- affected< iOS: 4.5.1
- affected< Android: 4.2
- affected< ChromeOS: 4.2
- affected< Linux: 3.7.2.64, 4.2.1.64
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.