dbcve.org
Client ConnectorApplication · Zscaler

CVE-2023-28799

MEDIUM · 6.1 CVSS v3.1 Published 2023-06-22
Fix available
A fix is available. Upgrade to 1.4 / 1.9.3 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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
A URL parameter during login flow was vulnerable to injection. An attacker could insert a malicious domain in this parameter, which would redirect the user after auth and send the authorization token to the redirected domain.

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 · moderate confidence

The login flow contains an insecure redirect parameter that accepts arbitrary domains. After successful authentication, the user is redirected to the attacker-controlled domain while the authorization token is appended to the redirect URL, enabling token exfiltration.

MitigationImplement strict allowlist validation for redirect URLs and remove tokens from redirect query parameters; use POST-based callbacks or server-side redirect validation instead.

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:< 1.4< 1.9.3< 1.10.1< 1.10.2< 3.7< 3.9

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

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. Locate Zscaler Client Connector installation
    Check Program Files for Zscaler Client Connector folder, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Where-Object {$_.DisplayName -like "*Zscaler*"}' in PowerShell
    Affected if Zscaler Client Connector is installed on the system
  2. Determine installed version number
    Run 'Get-ItemProperty "C:\Program Files\Zscaler\ZSClient\ZSClient.exe" -ErrorAction SilentlyContinue | Select-Object VersionInfo' or right-click the executable and view Properties > Details
    Affected if Version cannot be determined or shows an unlisted version
  3. Compare version against affected ranges
    Check if the installed version is less than 1.4, or between 1.4 and 1.9.2, or between 1.9.3 and 1.10.0, or between 1.10.1 and 1.10.1, or between 1.10.2 and 3.6, or between 3.7 and 3.8
    Affected if Installed version falls into any of these ranges: <1.4, <1.9.3, <1.10.1, <1.10.2, <3.7, <3.9
  4. Verify login flow is accessible
    Confirm Zscaler Client Connector is configured and users authenticate through it. Check if the client connects to Zscaler cloud and presents a login prompt
    Affected if Users authenticate through the Zscaler Client Connector login flow (this is the vulnerable component)

If Zscaler Client Connector is installed and its version falls within any of the affected ranges, the environment is vulnerable to token-exfiltrating redirects during login.

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.

dbcve · scoped
Upgrade available Upgrade to 1.4 / 1.9.3 / 1.10.1 or later
Fixed in 1.41.9.31.10.1
Interim mitigation

Implement strict allowlist validation for redirect URLs and remove tokens from redirect query parameters; use POST-based callbacks or server-side redirect validation instead.

Recommended fix High confidence

Zscaler Client Connector 1.10.2 (or the latest 1.10.x release, or the appropriate fixed version for your branch: 1.4+ for 1.x, 1.9.3+ for 1.9.x)

  1. Identify the currently installed Zscaler Client Connector version by checking Help > About or using the client interface
  2. Determine the current major version branch (1.x, 1.9.x, or 1.10.x)
  3. Download the appropriate fixed version: If on 1.x branch, upgrade to 1.4 or later; If on 1.9.x branch, upgrade to 1.9.3 or later; If on 1.10.x branch, upgrade to 1.10.2 or later
  4. Obtain the installer from the official Zscaler portal or your organization's software distribution point
  5. Close the Zscaler Client Connector application before upgrading
  6. Run the installer with appropriate administrative privileges
  7. Follow the on-screen installation prompts to complete the upgrade
  8. Verify the upgrade by checking the new version number in Help > About
Caveat Review Zscaler release notes for any compatibility changes or configuration requirements between your current and target version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Client Connector Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA3.0 h
19.0 hours of engineering $3,380
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,408.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-28799 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2023-28799 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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