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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 1 May 2024.
Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2024-20359

MEDIUM · 6.0 CVSS v3.1 Published 2024-04-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
In the wild Public exploit 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 a legacy capability that allowed for the preloading of VPN clients and plug-ins and that has been available in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to execute arbitrary code with root-level privileges. Administrator-level privileges are required to exploit this vulnerability. This vulnerability is due to improper validation of a file when it is read from system flash memory. An attacker could exploit this vulnerability by copying a crafted file to the disk0: file system of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the affected device after the next reload of the device, which could alter system behavior. Because the injected code could persist across device reboots, Cisco has raised the Security Impact Rating (SIR) of this advisory from Medium to High.

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 file validation vulnerability in Cisco ASA and FTD software's legacy VPN client preloading feature allows an authenticated admin attacker to place a crafted file on the disk0: flash filesystem, which upon device reload executes arbitrary code with root privileges. The malicious code persists across reboots.

MitigationApply Cisco security patches for ASA/FTD when available; restrict administrative access to trusted personnel only; monitor disk0: for unauthorized files; consider network segmentation to limit local access exposure.

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
Adaptive Security Appliance SoftwareOperating system
Affected:= 9.8.1= 9.8.1.5= 9.8.1.7= 9.8.2= 9.8.2.8= 9.8.2.14= 9.8.2.15= 9.8.2.17= 9.8.2.20= 9.8.2.24= 9.8.2.26= 9.8.2.28
Secure Firewall Threat DefenseApplication
Affected:= 6.2.3= 6.2.3.1= 6.2.3.2= 6.2.3.3= 6.2.3.4= 6.2.3.5= 6.2.3.6= 6.2.3.7= 6.2.3.8= 6.2.3.9= 6.2.3.10= 6.2.3.11

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

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

  1. Identify the device product type
    Log into the device CLI and run 'show version' or 'show inventory' to confirm whether the device runs Cisco ASA Software or Cisco Firepower Threat Defense (FTD)
    Affected if The device is not an ASA or FTD appliance - this CVE only applies to those products
  2. Check the installed ASA software version
    Run 'show version' in ASA CLI and locate the version string (for example, 9.8.2.20). Compare it exactly against the list: 9.8.1, 9.8.1.5, 9.8.1.7, 9.8.2, 9.8.2.8, 9.8.2.14, 9.8.2.15, 9.8.2.17, 9.8.2.20, 9.8.2.24, 9.8.2.26, 9.8.2.28
    Affected if The ASA version matches one of these exact versions exactly
  3. Check the installed FTD software version
    Run 'show version' in FTD CLI (or 'show version' via FMC) and locate the version string (for example, 6.2.3.9). Compare it exactly against the list: 6.2.3, 6.2.3.1, 6.2.3.2, 6.2.3.3, 6.2.3.4, 6.2.3.5, 6.2.3.6, 6.2.3.7, 6.2.3.8, 6.2.3.9, 6.2.3.10, 6.2.3.11
    Affected if The FTD version matches one of these exact versions exactly
  4. Verify legacy VPN client/preload functionality status
    Check if the legacy VPN client/preload feature is configured or enabled on the device. Look for related configuration with commands like 'show run all' or review configuration files for vpn-client or preload related entries
    Affected if Legacy VPN client or preload functionality is enabled - this is the vulnerable feature pathway
  5. Inspect disk0: flash filesystem for unauthorized files
    Run 'dir disk0:' in the device CLI to list files on the flash filesystem. Look for unfamiliar or suspicious files, particularly any that may have been placed prior to an unexpected device reload
    Affected if Unexpected or unauthorized files exist on disk0: that were not placed by known administrative actions

The device is affected only if it is a Cisco ASA or FTD appliance running exactly one of the listed versions AND the legacy VPN client/preload functionality is enabled, allowing an authenticated administrator to place a crafted file on disk0: for execution after reload

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco security patches for ASA/FTD when available; restrict administrative access to trusted personnel only; monitor disk0: for unauthorized files; consider network segmentation to limit local access exposure.

Fix this in Adaptive Security Appliance Software Exploited in the wild — priority engagement
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2024-20359 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