Secure Firewall Management CenterApplication · Cisco
CVE-2021-40114
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 in the way the Snort detection engine processes ICMP traffic that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper memory resource management while the Snort detection engine is processing ICMP packets. An attacker could exploit this vulnerability by sending a series of ICMP packets through an affected device. A successful exploit could allow the attacker to exhaust resources on the affected device, causing the 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 confidenceA vulnerability in Cisco's Snort detection engine allows an unauthenticated remote attacker to cause denial of service by sending specially crafted ICMP packets. The vulnerability stems from improper memory resource management during ICMP packet processing, which can exhaust device resources and cause the affected device to reload.
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
Secure Firewall Threat DefenseApplication
< 6.4.0.12>= 6.5.0, < 6.6.3>= 6.7.0, < 6.7.0.2
Unified Threat DefenseApplication
>= 16.12, < 16.12.6>= 17.3, < 17.3.4a>= 17.4, < 17.4.2>= 2.0.0, < 2.9.18CVSS 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 productDetermine if the system is running Cisco Firepower Threat Defense, Cisco Secure Firewall Management Center, Cisco Unified Threat Defense, or standalone Snort. Use 'show version' or check system documentation.Affected if The product is any of these four affected products
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Check the product versionRun 'show version' on the device CLI or check the management interface for the exact firmware/software version. For Snort, run 'snort --version'.Affected if The version falls within any of these ranges: FTD < 6.4.0.12, FTD 6.5.0 to < 6.6.3, FTD 6.7.0 to < 6.7.0.2; FMC = 2.9.14.0, = 2.9.15, = 2.9.16, or = 2.9.17; UTD >= 16.12 to < 16.12.6, >= 17.3 to < 17.3.4a, >= 17.4 to < 17.4.2; Snort >= 2.0.0 to < 2.9.18
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Verify Snort inspection is enabledCheck if the Snort intrusion prevention system is active on the device. On Firepower, use 'show snort statistics' or check the access control policy to confirm Snort is enabled for traffic inspection.Affected if Snort is actively inspecting traffic (the vulnerability only applies when Snort is running)
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Confirm ICMP inspection is activeVerify that ICMP traffic is being processed by Snort. Check the access control rules or intrusion policy to ensure ICMP packets are being inspected and not being dropped or excluded.Affected if ICMP traffic is being passed through Snort inspection (the crafted ICMP packets must reach the Snort engine for the vulnerability to trigger)
A user is affected if they are running any of the four affected products (or standalone Snort) within the specific version ranges AND have Snort enabled with ICMP traffic being inspected.
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 · scoped2.9.186.4.0.126.6.3
Apply Cisco's Snort detection engine updates and corresponding firmware patches for affected Cisco products. Consider implementing ICMP rate limiting or filtering at network boundaries as a temporary measure while patches are being deployed.
Snort 2.9.18; FTD 6.4.0.12/6.6.3/6.7.0.2; FMC 2.9.18; UTD 16.12.6/17.3.4a/17.4.2
- For Firepower Threat Defense (FTD): Upgrade to version 6.4.0.12, 6.6.3, or 6.7.0.2 depending on your current branch
- For Secure Firewall Management Center (FMC): Upgrade to version 2.9.18 or later
- For Unified Threat Defense (UTD): Upgrade to 16.12.6, 17.3.4a, or 17.4.2 depending on your current branch
- For standalone Snort: Upgrade to version 2.9.18 or later
- After upgrade, verify the Snort detection engine is running and the device is processing traffic normally
- Monitor device resources to confirm the ICMP packet handling no longer causes resource exhaustion
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Secure Firewall Management Center
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40114 — 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-2021-40114 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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