CVE-2021-1428

SYSTEM code execution via upgrade DLL hijacking

Published May 6, 2021 · Updated Nov 8, 2024

DLL hijacking in Cisco AnyConnect Secure Mobility Client for Windows before 4.10.00093 allows local users to execute code as SYSTEM. During an upgrade, the application loads a DLL from a user-writable directory, allowing a planted malicious library to run. Valid Windows credentials and initiation of an affected upgrade are required; successful exploitation grants SYSTEM-level code execution.

CVSS severity7.0
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DLL hijacking in Cisco AnyConnect Secure Mobility Client for Windows before 4.10.00093 allows local users to execute code as SYSTEM. During an upgrade, the application loads a DLL from a user-writable directory, allowing a planted malicious library to run. Valid Windows credentials and initiation of an affected upgrade are required; successful exploitation grants SYSTEM-level code execution.

The record

CVE
CVE-2021-1428
Published
May 6, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Secure Client
Classifications
CWE-427, CWE-378, T1574.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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=n/a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

ClamAV · Cisco Secure Clientversion=n/a

Published CVSS scores

7.0Cisco Systems, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST National Vulnerability DatabaseAV:L/AC:L/Au:N/C:C/I:C/A:C
7.8NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/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-427Uncontrolled Search Path Element
CWE-378Creation of Temporary File With Insecure Permissions
T1574.001Hijack Execution Flow: DLL

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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