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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2018-0231

HIGH · 8.6 CVSS v3.0 Published 2018-04-19
Fix available
A fix is available. Upgrade to 6.1.0.6 / 6.2.2.1 or later.
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 Transport Layer Security (TLS) library of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of the affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious TLS message to an interface enabled for Secure Layer Socket (SSL) services on an affected device. Messages using SSL Version 3 (SSLv3) or SSL Version 2 (SSLv2) cannot be be used to exploit this vulnerability. An exploit could allow the attacker to cause a buffer underflow, triggering a crash on an affected device. This vulnerability affects Cisco ASA Software and Cisco FTD Software that is running on the following Cisco products: Adaptive Security Virtual Appliance (ASAv), Firepower Threat Defense Virtual (FTDv), Firepower 2100 Series Security Appliance. Cisco Bug IDs: CSCve18902, CSCve34335, CSCve38446.

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 buffer underflow vulnerability in the TLS library of Cisco ASA and FTD software allows unauthenticated remote attackers to cause device reload by sending malicious TLS messages to SSL-enabled interfaces. The vulnerability stems from insufficient validation of user-supplied input in the TLS handshake processing. SSLv3 and SSLv2 messages cannot be used to exploit this issue.

MitigationApply the vendor-supplied software update (patch) to affected ASA or FTD installations. If immediate patching is not feasible, minimize exposure by restricting network access to SSL-enabled interfaces through ACLs or network segmentation.

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\(1\)= 98.1\(1.154\)
Secure Firewall Threat DefenseApplication
Affected:>= 6.0, < 6.1.0.6>= 6.2.1, < 6.2.2.1

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:3.0/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. Identify the device product type
    Run 'show version' to determine if the device is running Cisco ASA Software or Cisco Firepower Threat Defense (FTD)
    Affected if Device is Cisco ASA or FTD
  2. Check ASA software version
    Run 'show version' and locate the software version number. For ASA, compare against the 9.8(1) through 98.1(1.154) range
    Affected if ASA version is 9.8(1) through 98.1(1.154)
  3. Check FTD software version
    Run 'show version' and locate the software version number. For FTD, compare against 6.0 to 6.1.0.5 or 6.2.1 to 6.2.2.0
    Affected if FTD version is 6.0 to 6.1.0.5 or 6.2.1 to 6.2.2.0
  4. Verify SSL is enabled on any interface
    Run 'show ssl' or examine the configuration with 'show run ssl' to see if SSL/TLS is configured on any interface
    Affected if SSL or TLS is enabled on any interface (the vulnerability only affects SSL-enabled interfaces)

Device is affected if it is Cisco ASA version 9.8(1) to 98.1(1.154) or FTD version 6.0-6.1.0.5/6.2.1-6.2.2.0 AND has SSL/TLS enabled on at least one interface.

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 6.1.0.6 / 6.2.2.1 or later
Fixed in 6.1.0.66.2.2.1
Interim mitigation

Apply the vendor-supplied software update (patch) to affected ASA or FTD installations. If immediate patching is not feasible, minimize exposure by restricting network access to SSL-enabled interfaces through ACLs or network segmentation.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2018-0231 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