CVE-2021-1568

Local VPN Agent crash via crafted file

Published Jun 16, 2021 · Updated Nov 7, 2024

Uncontrolled memory allocation in Cisco AnyConnect Secure Mobility Client for Windows before 4.10.01075 allows local users to crash the VPN Agent. At application launch, the VPN Agent handles a crafted file placed in a specific system folder and allocates memory without enforcing a size limit. Valid credentials on a multiuser Windows system are required, and a successful exploit interrupts the VPN service for every user on that system.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uncontrolled memory allocation in Cisco AnyConnect Secure Mobility Client for Windows before 4.10.01075 allows local users to crash the VPN Agent. At application launch, the VPN Agent handles a crafted file placed in a specific system folder and allocates memory without enforcing a size limit. Valid credentials on a multiuser Windows system are required, and a successful exploit interrupts the VPN service for every user on that system.

The record

CVE
CVE-2021-1568
Published
Jun 16, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Secure Client
Classifications
CWE-789, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

5.5Cisco Systems, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:X/RL:X/RC:X
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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-789Memory Allocation with Excessive Size Value
T1499Endpoint Denial of Service

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo