dbcve.org
Anyconnect Secure Mobility ClientApplication · Cisco

CVE-2021-1258

MEDIUM · 5.5 CVSS v3.1 Published 2021-01-13
Fix available
A fix is available. Upgrade to 4.9.03047 / 4.9.03049 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

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 · unedited
A vulnerability in the upgrade component of Cisco AnyConnect Secure Mobility Client could allow an authenticated, local attacker with low privileges to read arbitrary files on the underlying operating system (OS) of an affected device. The vulnerability is due to insufficient file permission restrictions. An attacker could exploit this vulnerability by sending a crafted command from the local CLI to the application. A successful exploit could allow the attacker to read arbitrary files on the underlying OS of the affected device. The attacker would need to have valid user credentials to exploit this vulnerability.

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 · moderate confidence

A local privilege escalation vulnerability exists in the upgrade component of Cisco AnyConnect Secure Mobility Client. An authenticated attacker with low privileges can send crafted commands via the local CLI to read arbitrary files on the underlying operating system, due to insufficient file permission restrictions in the upgrade functionality.

MitigationApply vendor patches when available. Until then, restrict local CLI access to only trusted users and monitor for suspicious command execution patterns in upgrade components.

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
Affected:< 4.9.03047< 4.9.03049
Agent Epolicy Orchestrator ExtensionPlugin / extension
Affected:< 5.7.6

CVSS 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
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Verify Cisco AnyConnect installation
    Check for Cisco AnyConnect installation: On Windows, look in C:\Program Files\Cisco\Cisco AnyConnect Secure Mobility Client or check Programs and Features. On Linux, check /opt/cisco/anyconnect or run which vpn. On macOS, check /Applications/Cisco/
    Affected if AnyConnect is installed and the version is below 4.9.03047 or between 4.9.03048 and 4.9.03049 (exclusive)
  2. Determine installed AnyConnect version
    On Windows, open Add/Remove Programs and find Cisco AnyConnect Secure Mobility Client version, or run: C:\Program Files\Cisco\Cisco AnyConnect Secure Mobility Client\vpncli.exe -v. On Linux/Mac, run: /opt/cisco/anyconnect/bin/vpn -v
    Affected if Version number returned is less than 4.9.03047 or is 4.9.03048
  3. Confirm local CLI component presence
    Verify the CLI executable exists: On Windows check C:\Program Files\Cisco\Cisco AnyConnect Secure Mobility Client\vpncli.exe. On Linux check /opt/cisco/anyconnect/bin/vpncli. This CLI is the attack vector for the vulnerability.
    Affected if The vpncli executable exists and is accessible to low-privilege users on the system
  4. Check upgrade component file permissions
    On Windows, navigate to the AnyConnect installation directory and check permissions on files in the \lib\ or \upgrade\ subdirectories. Ensure low-privilege users cannot modify upgrade-related executables or configuration files.
    Affected if Upgrade component files are writable by non-privileged users or have weak permission restrictions

Your environment is affected if Cisco AnyConnect Secure Mobility Client is installed with a version below 4.9.03047 (or is version 4.9.03048) and the local CLI is accessible to low-privilege authenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 4.9.03047 / 4.9.03049 / 5.7.6 or later
Fixed in 4.9.030474.9.030495.7.6
Interim mitigation

Apply vendor patches when available. Until then, restrict local CLI access to only trusted users and monitor for suspicious command execution patterns in upgrade components.

Fix this in Anyconnect Secure Mobility Client Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-1258 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data