Anyconnect Secure Mobility ClientApplication · Cisco
CVE-2020-3435
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 · uneditedA vulnerability in the interprocess communication (IPC) channel of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated, local attacker to overwrite VPN profiles on an affected device. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a crafted IPC message to the AnyConnect process on an affected device. A successful exploit could allow the attacker to modify VPN profile files. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system.
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 · high confidenceThe Cisco AnyConnect Secure Mobility Client for Windows contains an IPC (interprocess communication) channel vulnerability that allows an authenticated local attacker to overwrite VPN profile files. The vulnerability stems from insufficient validation of user-supplied input in IPC messages sent to the AnyConnect process, enabling profile manipulation without proper authorization checks.
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
Anyconnect Secure Mobility ClientApplication
<= 4.9.00086CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Check installed AnyConnect versionOpen Programs and Features in Control Panel, or run 'wmic product get name,version' and look for Cisco AnyConnect Secure Mobility Client, or check the file version of C:\Program Files\Cisco\Cisco AnyConnect Secure Mobility Client\vpnui.exeAffected if The installed version is 4.9.00086 or lower (any version up to and including 4.9.00086)
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Verify AnyConnect IPC service is runningOpen Services console (services.msc) and locate the Cisco AnyConnect Secure Mobility Client service, or run 'sc query' to check for AnyConnect-related servicesAffected if The Cisco AnyConnect client service is installed and running on the system
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Check VPN profile directory permissionsNavigate to the profile storage location, typically C:\ProgramData\Cisco\Cisco AnyConnect Secure Mobility Client\Profile or C:\Users\%username%\AppData\Local\Cisco\AnyConnect\Profile, right-click the folder, go to Properties > Security, and review which users have Write or Modify permissionsAffected if Non-admin users have Write or Modify permissions to the profile storage directories, allowing profile manipulation
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Inspect AnyConnect installation directory permissionsNavigate to C:\Program Files\Cisco\Cisco AnyConnect Secure Mobility Client\, right-click the folder, go to Properties > Security, and verify that standard users (non-admins) have restricted permissionsAffected if Standard authenticated users have elevated permissions (Modify or Full Control) on the AnyConnect installation directory
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Monitor for suspicious IPC message activityUse process monitoring tools (such as Sysinternals Process Monitor) to filter for processes sending IPC messages to the AnyConnect.exe or vpnui.exe process, looking for unexpected write operations to profile filesAffected if Any process other than the legitimate AnyConnect components is writing to or modifying VPN profile XML files in the profile storage locations
A system is affected if Cisco AnyConnect Secure Mobility Client version 4.9.00086 or lower is installed and standard authenticated users have write access to the profile storage directories or AnyConnect installation directory, enabling unauthorized profile manipulation via IPC messages.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataApply the vendor patch from Cisco when available. Until then, restrict local user permissions to the AnyConnect installation directory and profile storage locations, and monitor for suspicious IPC messages to the AnyConnect process.
Fix this in Anyconnect Secure Mobility Client
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3435 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-3435 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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