Cloud Email SecurityApplication · Cisco
CVE-2020-3164
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 web-based management interface of Cisco AsyncOS for Cisco Email Security Appliance (ESA), Cisco Web Security Appliance (WSA), and Cisco Content Security Management Appliance (SMA) could allow an unauthenticated remote attacker to cause high CPU usage on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific HTTP request headers. An attacker could exploit this vulnerability by sending a malformed HTTP request to an affected device. A successful exploit could allow the attacker to trigger a prolonged status of high CPU utilization relative to the GUI process(es). Upon successful exploitation of this vulnerability, an affected device will still be operative, but its response time and overall performance may be degraded.
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 AsyncOS web-based management interface for ESA, WSA, and SMA allows unauthenticated attackers to cause denial of service by sending malformed HTTP requests with improperly validated headers, resulting in prolonged high CPU utilization on affected devices.
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
Cloud Email SecurityApplication
<= 13.0.0-392
Content Security Management ApplianceApplication
< 13.6.0
Email Security ApplianceApplication
<= 13.0.0-392
Web Security ApplianceApplication
<= 12.0.1-268CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 Cisco appliance modelAccess the device CLI or web interface and identify whether the device is an Email Security Appliance (ESA), Web Security Appliance (WSA), or Content Security Management Appliance (SMA). In the CLI, run the 'version' command to see the model name.Affected if The device is an ESA, WSA, or SMA model.
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Check the installed AsyncOS versionIn the device CLI, run the 'version' command to display the full version string including the build number (for example: 13.0.0-392). Compare this against the affected version ranges provided.Affected if For ESA or Cloud Email Security: version is 13.0.0-392 or lower. For WSA: version is 12.0.1-268 or lower. For SMA: version is below 13.6.0.
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Verify web-based management interface is enabledIn the web interface, navigate to Network > IP Interfaces or in the CLI run 'interfaceconfig' to confirm the management web interface (HTTP/HTTPS) is enabled on any interface. Also check if it is exposed to untrusted networks.Affected if The web-based management interface is enabled and accessible, particularly from untrusted networks.
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Check for symptoms of DoS conditionMonitor CPU utilization on the appliance. In the CLI, run 'status' or 'top' commands. Look for prolonged high CPU utilization even under normal traffic conditions, which could indicate exploitation.Affected if CPU utilization is abnormally high and sustained without corresponding legitimate traffic load.
The device is affected if it is an ESA, WSA, or SMA running an AsyncOS version within the affected ranges AND the web-based management interface is enabled and reachable.
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 data13.6.0
Apply Cisco security updates/patches for CVE-2020-3164 when released; meanwhile, consider implementing WAF rules or IPS signatures to filter malformed HTTP request headers targeting the management interface.
Fix this in Cloud Email Security
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,864.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3164 — 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-2020-3164 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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