dbcve.org
Asa 5506 X FirmwareOperating system · Cisco

CVE-2019-1873

HIGH · 8.6 CVSS v3.1 Published 2019-07-10
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 cryptographic driver for Cisco Adaptive Security Appliance Software (ASA) and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reboot unexpectedly. The vulnerability is due to incomplete input validation of a Secure Sockets Layer (SSL) or Transport Layer Security (TLS) ingress packet header. An attacker could exploit this vulnerability by sending a crafted TLS/SSL packet to an interface on the targeted device. An exploit could allow the attacker to cause the device to reload, which will result in a denial of service (DoS) condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. A valid SSL or TLS session is required 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 vulnerability in the cryptographic driver for Cisco ASA and FTD software contains incomplete input validation of SSL/TLS ingress packet headers. An unauthenticated remote attacker with a valid SSL/TLS session can send a crafted TLS/SSL packet to cause the device to unexpectedly reload, resulting in denial of service.

MitigationApply Cisco security updates when available; otherwise, limit exposure by restricting SSL/TLS traffic to affected interfaces using access controls, and monitor for repeated device reloads.

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
Asa 5506 X FirmwareOperating system
Affected:= 9.6\(4.16\)= 9.8\(3.8\)
Asa 5506h X FirmwareOperating system
Affected:= 9.6\(4.16\)= 9.8\(3.8\)
Asa 5506w X FirmwareOperating system
Affected:= 9.6\(4.16\)= 9.8\(3.8\)
Asa 5508 X FirmwareOperating system
Affected:= 9.6\(4.16\)= 9.8\(3.8\)
Asa 5516 X FirmwareOperating system
Affected:= 9.6\(4.16\)= 9.8\(3.8\)

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. Identify Cisco ASA model
    Run 'show version' or 'show hardware' command on the device CLI to confirm the specific ASA model (5506X, 5506HX, 5506WX, 5508X, or 5516X)
    Affected if The device is one of the listed models (5506X, 5506HX, 5506WX, 5508X, or 5516X)
  2. Check firmware version
    Run 'show version' and locate the 'Cisco ASA Software' version line. Extract the full version number in the format X.Y(Z)
    Affected if The firmware version is 9.6(4.16) or 9.8(3.8)
  3. Verify SSL/TLS inspection is enabled
    Run 'show run all service-policy' and look for inspection rules for SSL/TLS (inspect ssl), or check the access list applied to the ingress interface for SSL/TLS traffic inspection configuration
    Affected if SSL/TLS inspection is enabled on any interface handling incoming SSL/TLS traffic
  4. Confirm device accessibility
    Verify the device has an external or internal interface that accepts SSL/TLS connections from network attackers. Check the 'show run' for interface configurations and any 'inspect ssl' rules applied to outside or inside interfaces
    Affected if The device processes SSL/TLS traffic on accessible interfaces

The device is affected if it is an ASA 5506X/5506HX/5506WX/5508X/5516X model running firmware version 9.6(4.16) or 9.8(3.8) with SSL/TLS inspection enabled on a reachable 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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco security updates when available; otherwise, limit exposure by restricting SSL/TLS traffic to affected interfaces using access controls, and monitor for repeated device reloads.

Fix this in Asa 5506 X Firmware 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
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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-2019-1873 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