Secure Firewall Threat DefenseApplication · Cisco
CVE-2023-20270
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 interaction between the Server Message Block (SMB) protocol preprocessor and the Snort 3 detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the configured policies or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper error-checking when the Snort 3 detection engine is processing SMB traffic. An attacker could exploit this vulnerability by sending a crafted SMB packet stream through an affected device. A successful exploit could allow the attacker to cause the Snort process 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 · moderate confidenceThis vulnerability exists in the interaction between Cisco's SMB protocol preprocessor and the Snort 3 detection engine within Firepower Threat Defense software. Due to improper error-checking during SMB traffic processing, an attacker sending crafted SMB packets can either bypass configured security policies or trigger a Snort process reload, resulting in denial of service.
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
= 7.1.0= 7.1.0.1= 7.1.0.2= 7.1.0.3= 7.2.0= 7.2.0.1= 7.2.1= 7.2.2= 7.2.3= 7.3.0= 7.3.1= 7.3.1.1CVSS 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
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
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 Firepower Threat Defense versionRun 'show version' or access the Firepower Management Center to view the FTD device versionAffected if The displayed version matches one of: 7.1.0, 7.1.0.1, 7.1.0.2, 7.1.0.3, 7.2.0, 7.2.0.1, 7.2.1, 7.2.2, 7.2.3, 7.3.0, 7.3.1, or 7.3.1.1
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Verify the Snort detection engine in useCheck the intrusion policy configuration via the Firepower Management Center or run 'show snort version' if available on the FTD CLIAffected if Snort 3 is enabled as the detection engine for the intrusion policy inspecting traffic
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Confirm SMB traffic inspection is activeReview the access control or intrusion policy settings to determine if SMB protocol preprocessor or deep inspection is enabled for the policy applied to the trafficAffected if SMB traffic inspection or the SMB preprocessor is configured and active on the FTD device
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Determine if SMB traffic enters the FTD deviceReview network topology and access control rules to see if SMB traffic (TCP port 445 or related SMB ports) is permitted through the Firepower Threat Defense deviceAffected if SMB traffic from external or untrusted networks can reach the FTD device for inspection
You are affected if your FTD version is 7.1.0 through 7.3.1.1, Snort 3 is the active detection engine, SMB preprocessor inspection is enabled, and SMB traffic passes through the device.
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 · scopedApply the Cisco FTD software update that addresses this vulnerability when available from Cisco. Until then, consider filtering or restricting SMB traffic at network boundaries to reduce attack surface.
FTD 7.1.0.4 or later, or upgrade to 7.2.x/7.3.x stable branch
- Check current FTD version using 'show version' command
- Download the fixed FTD release (7.1.0.4 or later, or 7.2.x/7.3.x stable release) from Cisco
- Upload the new FTD image to the device using 'file' command
- Install the upgrade using 'upgrade' command
- Verify successful installation and Snort 3 engine version post-upgrade
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 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 $3,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-20270 — 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-2023-20270 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
- No weaponised exploit code, or anything meant to cause harm
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