Client Connector: Improper Handling of Values
CVE-2026-59565 is a high-severity improper handling of values vulnerability in Client Connector from Zscaler, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372 as the first without the flaw, so updating Client Connector to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Client Connector to Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zscaler | Client Connector | before Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372 | Windows: 4.6.0.457, 4.7.0.317, 4.8.0.232, 4.9.0.372 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (zscaler.com).
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Values
The product does not properly handle when the expected number of values for parameters, fields, or arguments is not provided in input, or if those values are undefined.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Client Connector
- 7.5 High severity
- 8.1 High severity
- 8.1 High severity
- 9.1 Critical severity
- 8.8 High severity
- 8.4 High severity
Recent Improper Handling of Values vulnerabilities
- 7.3 High severity
- 9.2 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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