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Client ConnectorApplication · Zscaler

CVE-2020-11635

HIGH · 7.8 CVSS v3.1 Published 2021-02-16
Fix available
A fix is available. Upgrade to 3.1.0 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The Zscaler Client Connector prior to 3.1.0 did not sufficiently validate RPC clients, which allows a local adversary to execute code with system privileges or perform limited actions for which they did not have privileges.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Zscaler Client Connector versions prior to 3.1.0 contain a local privilege escalation vulnerability in the RPC server component, which insufficiently validates client requests. This allows a local unauthenticated attacker to execute arbitrary code with SYSTEM-level privileges by sending specially crafted RPC requests.

MitigationUpgrade Zscaler Client Connector to version 3.1.0 or later to obtain the patched RPC client validation logic.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Client ConnectorApplication
Affected:< 3.1.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Zscaler Client Connector is installed
    Check for the presence of the Zscaler Client Connector service or executable. On Windows, open Services.msc and look for 'Zscaler Client Connector' or check Program Files for the Zscaler installation directory. Alternatively, query the registry key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{ZscalerClientConnector} or run 'Get-Service | Where-Object {$_.DisplayName -like *Zscaler*}' in PowerShell.
    Affected if The Zscaler Client Connector service or application is not found on the system.
  2. Identify the installed version number
    Locate the version information. In Windows, right-click the Zscaler Client Connector executable in Program Files and select Properties > Details, or query the registry at HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{ZscalerClientConnector} for the DisplayVersion value. The executable is typically named 'ZSCClientConnector.exe' located in C:\Program Files\Zscaler\ZSClient\ or C:\Program Files (x86)\Zscaler\ZSClient\.
    Affected if Unable to determine the version number.
  3. Compare version against the affected range
    Review the identified version against the affected range. Versions prior to 3.1.0 are vulnerable. Version 3.1.0 and later include the patched RPC client validation logic. Format is typically major.minor.build (e.g., 3.0.95, 2.9.120).
    Affected if The installed version is lower than 3.1.0 (e.g., 3.0.x, 2.x.x).
  4. Verify the RPC server component status
    The vulnerability resides in the RPC server component. Check if the Zscaler Client Connector service is running by opening Services.msc and confirming the service status is 'Running', or run 'Get-Service ZscalerClientConnector' in PowerShell. The RPC server is enabled by default when the service runs.
    Affected if The Zscaler Client Connector service is running with a version lower than 3.1.0.

The system is affected if Zscaler Client Connector is installed with a version lower than 3.1.0 and the service is running, as this combination allows the vulnerable RPC server component to be active and exploitable for local privilege escalation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 3.1.0 or later
Fixed in 3.1.0
Interim mitigation

Upgrade Zscaler Client Connector to version 3.1.0 or later to obtain the patched RPC client validation logic.

Fix this in Client Connector Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-11635 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data