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Adaptive Security Appliance SoftwareApplication · Cisco

CVE-2019-1687

HIGH · 7.5 CVSS v3.1 Published 2019-05-03
Fix available
A fix is available. Upgrade to 6.2.3.12 / 6.3.0.3 or later.
See remediation →
84/100
Remediation priority · High
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 TCP proxy functionality for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to restart unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability is due to an error in TCP-based packet inspection, which could cause the TCP packet to have an invalid Layer 2 (L2)-formatted header. An attacker could exploit this vulnerability by sending a crafted TCP packet sequence to the targeted device. A successful exploit could allow the attacker to cause a DoS condition.

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 vulnerability in the TCP proxy inspection functionality of Cisco ASA and FTD Software allows crafted TCP packets to trigger an invalid Layer 2-formatted header, causing the device to reload unexpectedly and result in denial of service.

MitigationApply Cisco security updates for ASA and FTD software; until patched, consider network-level filtering of suspicious TCP packet sequences and implement high-availability failover to minimize downtime.

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 SoftwareApplication
Affected:< 9.4.4.34>= 9.5, < 9.6.4.25>= 9.7, < 9.8.4>= 9.9, < 9.9.2.50>= 9.10, < 9.10.1.17
Secure Firewall Threat DefenseApplication
Affected:>= 6.0.0, < 6.2.3.12>= 6.3.0, < 6.3.0.3

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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 Cisco product running
    Run 'show version' or 'show module' command to determine if the device is running Cisco ASA or Firepower Threat Defense (FTD) software
    Affected if The device runs ASA or FTD software and the version falls within the affected ranges
  2. Check the installed ASA version
    Execute 'show version' and locate the ASA software version number (e.g., 9.8.3)
    Affected if The ASA version is < 9.4.4.34, OR >= 9.5 and < 9.6.4.25, OR >= 9.7 and < 9.8.4, OR >= 9.9 and < 9.9.2.50, OR >= 9.10 and < 9.10.1.17
  3. Check the installed FTD version
    Execute 'show version' or access the FTD management interface to determine the FTD software version
    Affected if The FTD version is >= 6.0.0 and < 6.2.3.12, OR >= 6.3.0 and < 6.3.0.3
  4. Verify TCP inspection is enabled
    Run 'show running-config | include inspection' or access the ASA/FTD policy-map configuration to list active inspection features
    Affected if TCP inspection (inspect tcp or tcp-proxy) is configured in the active security policy
  5. Check for TCP proxy inspection specifically
    Examine the policy-map configuration with 'show running-config policy-map' and look for tcp-proxy or TCP inspection entries tied to traffic inspection policies
    Affected if TCP proxy inspection is explicitly enabled in an inspection policy applied to traffic

A device is affected if it runs a vulnerable ASA or FTD version AND has TCP inspection or TCP proxy inspection enabled in its security policy, as the vulnerability triggers through this feature.

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 6.2.3.12 / 6.3.0.3 / 9.4.4.34 or later
Fixed in 6.2.3.126.3.0.39.4.4.34
Interim mitigation

Apply Cisco security updates for ASA and FTD software; until patched, consider network-level filtering of suspicious TCP packet sequences and implement high-availability failover to minimize downtime.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,580
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,128.

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-2019-1687 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