Secure Firewall Threat DefenseApplication · Cisco
CVE-2021-1422
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 software cryptography module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker or an unauthenticated attacker in a man-in-the-middle position to cause an unexpected reload of the device that results in a denial of service (DoS) condition. The vulnerability is due to a logic error in how the software cryptography module handles specific types of decryption errors. An attacker could exploit this vulnerability by sending malicious packets over an established IPsec connection. A successful exploit could cause the device to crash, forcing it to reload. Important: Successful exploitation of this vulnerability would not cause a compromise of any encrypted data. Note: This vulnerability affects only Cisco ASA Software Release 9.16.1 and Cisco FTD Software Release 7.0.0.
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 logic error in the software cryptography module of Cisco ASA and FTD causes the device to unexpectedly reload when handling specific decryption errors. An authenticated remote attacker or man-in-the-middle attacker can send malicious packets over an established IPsec connection to trigger the crash and force a denial of service. Only Cisco ASA 9.16.1 and FTD 7.0.0 are affected.
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
= 7.0.0.0
Adaptive Security Appliance SoftwareOperating system
= 9.16.1CVSS 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
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify device type and software versionLog into the device CLI and run 'show version' to confirm whether the device is running Cisco ASA Software or Cisco Firepower Threat Defense (FTD) software, and note the exact version number displayed.Affected if The device is running Cisco ASA Software version 9.16.1 or Cisco FTD version 7.0.0.0
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Verify IPsec configuration statusRun 'show crypto ipsec sa' or 'show isakmp sa' to check if any IPsec Security Associations (SAs) are active on the device.Affected if Any active IPsec SAs exist - this indicates the device is using IPsec, which is required for the attack vector to be exploitable.
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Confirm software cryptography module is in useRun 'show crypto engine' or check the crypto configuration with 'show running-config crypto' to verify the software cryptography module is enabled.Affected if The software cryptography module is enabled and handling IPsec traffic - the vulnerability exists in the software crypto module specifically.
You are affected only if your device is Cisco ASA 9.16.1 or FTD 7.0.0.0 AND you have active IPsec connections using the software cryptography module; other versions or configurations are not vulnerable to this specific flaw.
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.
From vendor dataApply the Cisco software update that addresses this vulnerability; until then, consider IPsec connection monitoring and potential network segmentation to reduce exposure.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 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 $4,128.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1422 — 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-2021-1422 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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