Client Connector: Improper Handling of Values
CVE-2026-59566 is a high-severity improper handling of values vulnerability in Client Connector from Zscaler, with a CVSS 3.1 base score of 8.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists versions Android: 4.2, ChromeOS: 4.2 as the first without the flaw, so updating Client Connector to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% 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 Android: 4.2 or ChromeOS: 4.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zscaler | Client Connector | before Android: 4.2; before ChromeOS: 4.2 | Android: 4.2, ChromeOS: 4.2 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (zscaler.com).
Official description
A locally exploitable buffer overflow bug can cause a local denial-of-service attack on affected versions of Zscaler Client Connector on Android and ChromeOS.
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
- 8.8 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
Spotted an error? Tell us.