CVE-2021-26735

SYSTEM code execution via unquoted uninstaller path

Published Oct 23, 2023 · Updated Feb 27, 2025

Unquoted search paths in Zscaler Client Connector before 3.6 allow local users to execute code with SYSTEM privileges during uninstall. The installer and uninstallers invoke REG DELETE through an unquoted path, allowing an earlier path element to resolve to attacker-controlled code. Exploitation requires local filesystem access and user interaction with an install or uninstall operation; successful code runs as SYSTEM.

CVSS severity6.7
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unquoted search paths in Zscaler Client Connector before 3.6 allow local users to execute code with SYSTEM privileges during uninstall. The installer and uninstallers invoke REG DELETE through an unquoted path, allowing an earlier path element to resolve to attacker-controlled code. Exploitation requires local filesystem access and user interaction with an install or uninstall operation; successful code runs as SYSTEM.

The record

CVE
CVE-2021-26735
Published
Oct 23, 2023
Updated
Feb 27, 2025
Vendor
Zscaler
Product
Zscaler Client Connector
Classifications
CWE-428, CWE-346, T1574.009
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 2025Record 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 <3.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Zscaler · Zscaler Client Connectorversion=0 <3.6

Published CVSS scores

7.8National Institute of Standards and TechnologyCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.7Zscaler, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-428Unquoted Search Path or Element
CWE-346Origin Validation Error
T1574.009Hijack Execution Flow: Path Interception by Unquoted Path

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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