CVE-2023-28806

Anti-tampering bypass via improper DLL signature verification

Published Aug 6, 2024 · Updated Aug 6, 2024

Improper signature verification in Zscaler Client Connector for Windows before 4.2.0.190 allows local users to disable anti-tampering. A client DLL incorrectly verifies a cryptographic signature used by the anti-tampering control; Zscaler has not disclosed the DLL name or exact validation operation. Exploitation requires high local privileges and high complexity, and the bounded consequence is loss of the client's anti-tampering protection.

CVSS severity6.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Zscaler Client Connector for Windows before 4.2.0.190 allows local users to disable anti-tampering. A client DLL incorrectly verifies a cryptographic signature used by the anti-tampering control; Zscaler has not disclosed the DLL name or exact validation operation. Exploitation requires high local privileges and high complexity, and the bounded consequence is loss of the client's anti-tampering protection.

The record

CVE
CVE-2023-28806
Published
Aug 6, 2024
Updated
Aug 6, 2024
Vendor
Zscaler
Product
Zscaler Client Connector
Classifications
CWE-347, CAPEC-207, T1562.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Aug 6, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4.2.0.190

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Zscaler · Zscaler Client Connectorversion=0 <4.2.0.190

Published CVSS scores

5.7ZscalerCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CAPEC-207Removing Important Client Functionality
T1562.001Impair Defenses: Disable or Modify Tools

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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