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Secure Firewall Threat DefenseApplication · Cisco

CVE-2021-34792

HIGH · 7.5 CVSS v3.1 Published 2021-10-27
Fix available
A fix is available. Upgrade to 6.4.0.13 / 6.6.5 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 memory management of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper resource management when connection rates are high. An attacker could exploit this vulnerability by opening a significant number of connections on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in 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

Memory management vulnerability in Cisco ASA and FTD software where improper resource management during high connection rates allows an unauthenticated remote attacker to cause device reload, resulting in denial of service.

MitigationApply the vendor-supplied security update/patch for Cisco ASA and FTD software to remediate this vulnerability.

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, < 6.4.0.13>= 6.6.0, < 6.6.5>= 6.7.0, < 6.7.0.3>= 7.0.0, < 7.0.1
Adaptive Security Appliance SoftwareOperating system
Affected:>= 9.8.0, < 9.8.4.40>= 9.12.0, < 9.12.4.29>= 9.14.0, < 9.14.3.9>= 9.15.0, < 9.15.1.17>= 9.16.0, < 9.16.2.3
Asa 5512 X FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)
Asa 5505 FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)
Asa 5515 X FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)
Asa 5525 X FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)
Asa 5545 X FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)
Asa 5555 X FirmwareOperating system
Affected:= 009.014\(001.150\)= 099.017\(001.211\)= 099.017\(001.220\)= 099.017\(015.050\)

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. Confirm device is Cisco ASA or FTD
    Identify the device type via show version or inventory - look for 'Cisco Adaptive Security Appliance' or 'Firepower Threat Defense' in the output
    Affected if Device is not a Cisco ASA or FTD appliance (other Cisco devices are not affected by this CVE)
  2. Obtain the software version
    Run 'show version' on the ASA CLI or use 'show version' in FTD CLI. Look for the 'Cisco Adaptive Security Appliance Software' or 'Firepower Threat Defense' version number
    Affected if Unable to retrieve version information from the device
  3. Compare ASA version against affected ranges
    Match the obtained ASA version number to these vulnerable ranges: 9.8.0 through 9.8.4.39, 9.12.0 through 9.12.4.28, 9.14.0 through 9.14.3.8, 9.15.0 through 9.15.1.16, 9.16.0 through 9.16.2.2
    Affected if ASA version falls within any of these ranges
  4. Compare FTD version against affected ranges
    Match the obtained FTD version number to these vulnerable ranges: 6.4.0 through 6.4.0.12, 6.6.0 through 6.6.4, 6.7.0 through 6.7.0.2, 7.0.0 through 7.0.0
    Affected if FTD version falls within any of these ranges
  5. Check ASA firmware for specific affected versions
    For ASA 5505, 5512X, 5515X, 5525X, 5545X, 5555X - run 'show version' and look for firmware build numbers: 009.014(001.150), 099.017(001.211), 099.017(001.220), or 099.017(015.050)
    Affected if ASA firmware build matches any of these four specific versions

Your device is affected if it is a Cisco ASA or FTD appliance running a software or firmware version that falls within the listed vulnerable ranges, as the vulnerability triggers during high connection rates and can cause device reload.

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.

dbcve · scoped
Upgrade available Upgrade to 6.4.0.13 / 6.6.5 / 6.7.0.3 or later
Fixed in 6.4.0.136.6.56.7.0.3
Interim mitigation

Apply the vendor-supplied security update/patch for Cisco ASA and FTD software to remediate this vulnerability.

Recommended fix High confidence

Firepower Threat Defense: upgrade to 6.4.0.13, 6.6.5, or 7.0.1 (depending on your current release train). ASA Software: upgrade to 9.8.4.40, 9.12.4.29, 9.14.3.9, or 9.15.1.17

  1. 1. Identify the currently installed Cisco ASA Software or FTD version by running the 'show version' command on the device
  2. 2. Determine which upgrade path applies based on your current version from the affected versions list
  3. 3. Access Cisco's software download page (tools.cisco.com) and download the appropriate fixed version for your device model
  4. 4. Transfer the software image to the device using FTP, SCP, or through the management interface
  5. 5. Install the new software image using the 'install' command or through the ASDM/FTD management interface
  6. 6. After installation, reload the device using the 'reload' command to complete the upgrade
  7. 7. Verify the upgrade was successful by running 'show version' and confirm the new version is installed
  8. 8. Verify normal device operation and that the vulnerability is mitigated
Caveat Review Cisco release notes for any configuration changes or compatibility considerations between your current version and the target fixed version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,968.

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-2021-34792 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