Secure Firewall Threat DefenseApplication · Cisco
CVE-2021-34704
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 · uneditedA vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition. This vulnerability is due to improper input validation when parsing HTTPS requests. An attacker could exploit this vulnerability by sending a malicious HTTPS request to 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 confidenceA vulnerability in the web services interface of Cisco ASA and FTD allows an unauthenticated remote attacker to cause a denial of service by sending malicious HTTPS requests. The vulnerability stems from improper input validation during HTTPS request parsing, which triggers a device reload when successfully exploited.
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
>= 6.7.0, < 6.7.0.3= 7.0.0
Adaptive Security Appliance SoftwareOperating system
>= 9.15, < 9.15.1.17>= 9.16, < 9.16.2CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the installed product typeRun 'show version' or check the device management interface to confirm whether the device runs Cisco ASA Software or Cisco Firepower Threat Defense (FTD).Affected if The device runs either Cisco ASA or FTD software.
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Determine the ASA software versionOn ASA devices, run the command 'show version' and locate the 'Cisco ASA Software' version line. Compare the version number to the affected ranges: 9.15.x versions before 9.15.1.17, or 9.16.x versions before 9.16.2.Affected if The ASA version is 9.15.x (before 9.15.1.17) or 9.16.x (before 9.16.2).
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Determine the FTD software versionOn FTD devices, run 'show version' and locate the 'Cisco Firepower Threat Defense' version. Compare to affected ranges: 6.7.0 through 6.7.0.2, or exactly version 7.0.0.Affected if The FTD version is 6.7.0.x (any version before 6.7.0.3) or exactly 7.0.0.
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Check if the web services interface is accessibleVerify whether HTTPS ports (typically 443) on the device management interfaces are exposed to untrusted networks. Use 'show interface' and review access-list configurations to determine if the web services interface can be reached from external or untrusted IP addresses.Affected if The web services interface (HTTPS management access) is reachable from untrusted or external networks.
A device is affected if it runs a vulnerable ASA or FTD version AND has its web services interface accessible to untrusted networks, allowing remote attackers to send malicious HTTPS requests that can trigger a device reload.
Generated from the published advisory. Verify against your own configuration.
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 · scoped6.7.0.39.15.1.179.16.2
Apply the vendor-supplied software update from Cisco's security advisory. If immediate patching is not possible, restrict access to the web services interface to trusted IP addresses only.
FTD: 6.7.0.3+ or 7.0.1+; ASA: 9.15.1.17+ or 9.16.2+
- 1. Identify the currently installed Cisco ASA or FTD software version using 'show version' command
- 2. Determine which product line and version branch you are running (ASA or FTD, and the specific version number)
- 3. For Firepower Threat Defense (FTD): If running 6.7.0.x versions, upgrade to 6.7.0.3 or later; if running 7.0.0, upgrade to 7.0.1 or later
- 4. For Adaptive Security Appliance (ASA): If running 9.15.x, upgrade to 9.15.1.17 or later; if running 9.16.x, upgrade to 9.16.2 or later
- 5. Download the appropriate fixed software image from Cisco's download portal (software.cisco.com) using valid SMART Net or similar support contract
- 6. Upload the new image to the device using the device's management interface
- 7. Install the new image and reload the device using the 'install' command or equivalent procedure
- 8. After reload, verify the new version is installed with 'show version' and confirm the device is functioning normally
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
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,728.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-34704 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-34704 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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