Secure Firewall Threat DefenseApplication · Cisco
CVE-2019-1703
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 internal packet-processing functionality of Cisco Firepower Threat Defense (FTD) Software for the Cisco Firepower 2100 Series could allow an unauthenticated, remote attacker to cause an affected device to stop processing traffic, resulting in a denial of service (DoS) condition. The vulnerability is due to a logic error, which may prevent ingress buffers from being replenished under specific traffic conditions. An attacker could exploit this vulnerability by sending a series of crafted packets to an affected device. A successful exploit could allow the attacker to consume all input buffers, which are shared between all interfaces, leading to a queue wedge condition in all active interfaces. This situation would cause an affected device to stop processing any incoming traffic and result in a DoS condition until the device is reloaded manually.
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 internal packet-processing functionality of Cisco FTD Software for Firepower 2100 Series prevents ingress buffers from being replenished under specific traffic conditions. An attacker sending crafted packets can exhaust all shared input buffers, causing a queue wedge condition across all active interfaces and forcing the device to stop processing traffic until manual 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 Threat DefenseApplication
>= 6.2.1, < 6.2.3.12CVSS 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
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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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Verify Firepower 2100 hardware modelExecute 'show version' or 'show inventory' on the FTD device CLI to confirm the hardware platform is Firepower 2100 SeriesAffected if Device is not a Firepower 2100 Series - this CVE only affects that specific platform
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Check installed FTD software versionRun 'show version' and locate the 'Cisco Firepower Threat Defense' version string. Compare it against the affected range: >= 6.2.1 and < 6.2.3.12Affected if Version falls within >= 6.2.1 and < 6.2.3.12
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Inspect interface queue status for wedge conditionRun 'show interface' or 'show interface statistics' to check if all interfaces show queue wedge or zero packet processingAffected if Interfaces show persistent queue wedged state with no traffic being processed despite valid link status
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Check system buffer exhaustionRun 'show memory' or 'show system buffers' to confirm shared input buffers are fully consumed and not recoveringAffected if Input buffer pool shows 100% utilization with no replenishment occurring over time
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Verify traffic has stopped across all active interfacesRun 'show traffic' or 'show conn count' to confirm no new connections or packet counts are incrementing on any interfaceAffected if All active interfaces show zero packet incrementation even when traffic is expected
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Confirm device requires manual reload to restore operationAfter observing the wedge condition, verify that power cycle or reload is needed to resume packet processingAffected if Reloading the device is the only method that restores traffic processing capability
Device is affected if it is a Firepower 2100 Series running FTD version 6.2.1 through 6.2.3.11 and exhibits symptoms of complete interface queue wedge with no traffic processing despite active links.
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 data6.2.3.12
Apply the Cisco-provided software update/patch for FTD when available; prior to patching, implement traffic rate limiting and monitoring to detect abnormal packet patterns. Manual device reload is required to restore functionality once the DoS condition occurs.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-1703 — 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-2019-1703 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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