On affected versions of Zscaler client connector, a pre-installed peer app can tear down the…
CVE-2026-59570 is a high-severity improper input validation vulnerability in Client Connector from Zscaler, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions Android: 4.2.0.152, ChromeOS: 4.2.0.152 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 0.13% 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: 4.2.0.152 or ChromeOS: 4.2.0.152, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zscaler | Client Connector | before Android: 4.2.0.152; before ChromeOS: 4.2.0.152 | Android: 4.2.0.152, ChromeOS: 4.2.0.152 |
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
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:H. Scored by CNA (zscaler.com).
Official description
On affected versions of Zscaler client connector, a pre-installed peer app can tear down the Zscaler tunnel, force user logout, and toggle packet capture.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How developers prevent this class of flaw
- Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
- Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Client Connector
- 8.1 High severity
- 8.1 High severity
- 9.1 Critical severity
- 8.8 High severity
- 8.4 High severity
- 8.8 High severity
Recent Improper Input Validation vulnerabilities
- 9.1 Critical severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 8.5 High severity
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