Secure Firewall Management CenterApplication · Cisco
CVE-2021-1224
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 · uneditedMultiple Cisco products are affected by a vulnerability with TCP Fast Open (TFO) when used in conjunction with the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP. The vulnerability is due to incorrect detection of the HTTP payload if it is contained at least partially within the TFO connection handshake. An attacker could exploit this vulnerability by sending crafted TFO packets with an HTTP payload through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.
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 confidenceThis vulnerability affects Cisco products using TCP Fast Open (TFO) with the Snort detection engine. The issue is that Snort incorrectly detects HTTP payloads when they are contained at least partially within the TFO connection handshake. An attacker can send crafted TFO packets containing HTTP payloads to bypass configured file policies and deliver malicious content.
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 Management CenterApplication
= 2.9.14.0= 2.9.15= 2.9.16= 2.9.17= 2.9.18= 3.0.1
Secure Firewall Threat DefenseApplication
< 6.7.0
Ios XeOperating system
< 17.4.1
Meraki Mx64 FirmwareOperating system
all versions
Meraki Mx64w FirmwareOperating system
all versions
Meraki Mx67 FirmwareOperating system
all versions
Meraki Mx67c FirmwareOperating system
all versions
Meraki Mx67w FirmwareOperating system
all versionsCVSS 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
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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 your Cisco product and versionDetermine the exact product model and installed software version from device management interfaces or CLI outputAffected if Product is Cisco Firepower Threat Defense, Secure Firewall Management Center, IOS Xe, or Meraki MX64/MX64w/MX67/MX67c/MX67w and version falls within affected ranges (< 6.7.0 for FTD, specific versions for FMC, < 17.4.1 for IOS Xe, any version for Meraki)
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Verify Snort detection engine is in useConfirm that the Snort intrusion detection/prevention engine is enabled on the deviceAffected if Snort is the active detection engine (this is required for the vulnerability to apply)
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Check if TCP Fast Open is enabledInspect device configuration for TFO settings via CLI or management interface. Look for TCP Fast Open, TFO, or fast-open related configuration options.Affected if TFO is enabled on the device - this is the condition that makes the vulnerability exploitable
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Review file policy configuration for HTTP inspectionExamine configured file policies and HTTP inspection rules to understand what content should be blockedAffected if File policies exist that should inspect HTTP traffic - the vulnerability allows bypass of these policies
You are affected if your device is an affected Cisco product/version AND TFO is enabled AND Snort is used for detection, because the vulnerability allows HTTP payloads in TFO handshakes to bypass configured file policies.
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 data6.7.017.4.1
Apply Cisco security updates for affected products. If patches are unavailable, consider disabling TFO on affected devices or implementing additional network-level controls to inspect TFO traffic.
Fix this in Secure Firewall Management Center
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1224 — 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-2021-1224 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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