dbcve.org
Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2024-20494

HIGH · 8.6 CVSS v3.1 Published 2024-10-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges 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 TLS cryptography functionality of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper data validation during the TLS 1.3 handshake. An attacker could exploit this vulnerability by sending a crafted TLS 1.3 packet to an affected system through a TLS 1.3-enabled listening socket. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: This vulnerability can also impact the integrity of a device by causing VPN HostScan communication failures or file transfer failures when Cisco ASA Software is upgraded using Cisco Adaptive Security Device Manager (ASDM).

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 confidence

A data validation vulnerability in the TLS 1.3 handshake processing of Cisco ASA and FTD software allows unauthenticated remote attackers to send crafted TLS 1.3 packets that cause unexpected device reloads, resulting in denial of service. The flaw can also disrupt VPN HostScan communication and file transfers during ASDM upgrades.

MitigationApply the relevant Cisco security update (software patch) for ASA/FTD. If immediate patching is not possible, consider restricting TLS 1.3 exposure or implementing additional network-level controls to limit exposure to unauthenticated TLS traffic.

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:= 9.19.1= 9.19.1.5= 9.19.1.9= 9.19.1.12= 9.19.1.18= 9.19.1.22= 9.19.1.24= 9.19.1.27= 9.19.1.28= 9.19.1.31= 9.20.1= 9.20.1.5
Secure Firewall Threat DefenseApplication
Affected:= 7.3.0= 7.3.1= 7.3.1.1= 7.3.1.2= 7.4.0= 7.4.1= 7.4.1.1= 7.4.2

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

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

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. Check ASA software version
    Run `show version` on the ASA CLI and locate the 'Cisco Adaptive Security Appliance Software' version line
    Affected if Version matches any of: 9.19.1, 9.19.1.5, 9.19.1.9, 9.19.1.12, 9.19.1.18, 9.19.1.22, 9.19.1.24, 9.19.1.27, 9.19.1.28, 9.19.1.31, 9.20.1, or 9.20.1.5
  2. Check FTD software version
    Run `show version` on the FTD device CLI and locate the 'Cisco Firepower Threat Defense' version line
    Affected if Version matches any of: 7.3.0, 7.3.1, 7.3.1.1, 7.3.1.2, 7.4.0, 7.4.1, 7.4.1.1, or 7.4.2
  3. Verify TLS 1.3 is enabled on ASA
    Run `show run all ssl` or `show ssl <interface>` to inspect SSL/TLS configuration. Look for 'version tlsv1.3' in the output
    Affected if TLS 1.3 is listed as enabled on any interface (the vulnerability requires TLS 1.3 to be active)
  4. Verify TLS 1.3 is enabled on FTD
    Access the Firepower Management Center or run `show ssl` CLI command to check SSL profiles. Look for TLS 1.3 configuration in SSL policy settings
    Affected if TLS 1.3 is configured in any SSL profile or policy

A device is affected if it runs an affected ASA or FTD version AND has TLS 1.3 enabled on at least one interface; devices without TLS 1.3 enabled are not vulnerable to this flaw.

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 the relevant Cisco security update (software patch) for ASA/FTD. If immediate patching is not possible, consider restricting TLS 1.3 exposure or implementing additional network-level controls to limit exposure to unauthenticated TLS traffic.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,440
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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-2024-20494 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