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Secure Firewall Threat DefenseApplication · Cisco

CVE-2020-3283

HIGH · 8.6 CVSS v3.1 Published 2020-05-06
Fix available
A fix is available. Upgrade to 6.4.0.9 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 Secure Sockets Layer (SSL)/Transport Layer Security (TLS) handler of Cisco Firepower Threat Defense (FTD) Software when running on the Cisco Firepower 1000 Series platform could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. The vulnerability is due to a communication error between internal functions. An attacker could exploit this vulnerability by sending a crafted SSL/TLS message to an affected device. A successful exploit could allow the attacker to cause a buffer underrun, which leads to a crash. The crash causes the affected device to reload.

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 underrun vulnerability in the SSL/TLS handler of Cisco FTD software on Firepower 1000 Series devices allows unauthenticated remote attackers to crash and force a device reload by sending crafted SSL/TLS messages. The flaw stems from a communication error between internal functions during TLS message processing.

MitigationApply the Cisco FTD software update for CVE-2020-3283 from the Cisco support portal; ensure the Firepower 1000 Series receives the patched version and schedule a maintenance window for the update with post-patch connectivity testing.

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
Secure Firewall Threat DefenseApplication
Affected:>= 6.4.0, < 6.4.0.9
Asa 5505 FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5510 FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5512 X FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5515 X FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5520 FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5525 X FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)
Asa 5540 FirmwareOperating system
Affected:= 9.12\(2.12\)= 9.13\(0.33\)

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 the Cisco device model and software type
    Log into the device CLI or check the device inventory. For FTD, run 'show version' or check Firepower Management Center. For ASA, run 'show version' from privileged mode.
    Affected if The device is a Firepower 1000 Series running FTD, or an ASA 5505/5510/5512X/5515X/5520/5525X/5540.
  2. Determine the Firepower Threat Defense version
    Run 'show version' on the FTD device or check the Firepower Management Center for the FTD version. Note the full version string including the maintenance release number.
    Affected if The FTD version is 6.4.0 through 6.4.0.8 (any version >= 6.4.0 but < 6.4.0.9).
  3. Determine the ASA firmware version
    Run 'show version' on the ASA device. Look for the version string in the format 9.12(x.xx) or 9.13(x.xx).
    Affected if The ASA firmware version is exactly 9.12(2.12) or 9.13(0.33).
  4. Verify SSL/TLS inspection is enabled
    Check the FTD or ASA configuration for SSL/TLS inspection policies. On FTD, use 'show running-config | include ssl' or check the inspection policy map. On ASA, run 'show service-policy | include inspection' and verify SSL inspection is active.
    Affected if SSL/TLS inspection or decryption is configured and active on the device interface exposed to network traffic.
  5. Check device accessibility and recent crash logs
    Review system logs and crashinfo files for recent reloads. Run 'show crashinfo' or check syslog for unexpected reloads. Look for TLS-related error messages preceding any recent device reloads.
    Affected if The device has experienced unexplained reloads or TLS-related crashes since the affected version was deployed.

A user is affected if their device is a Firepower 1000 Series running FTD version 6.4.0-6.4.0.8, or an ASA model from the list running firmware 9.12(2.12) or 9.13(0.33), with SSL/TLS inspection enabled and the device exposed to untrusted network traffic.

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 6.4.0.9 or later
Fixed in 6.4.0.9
Interim mitigation

Apply the Cisco FTD software update for CVE-2020-3283 from the Cisco support portal; ensure the Firepower 1000 Series receives the patched version and schedule a maintenance window for the update with post-patch connectivity testing.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.

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-2020-3283 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