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Email Security Appliance FirmwareOperating system · Cisco

CVE-2016-6463

MEDIUM · 5.3 CVSS v3.0 Published 2016-11-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability in the email filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to bypass Advanced Malware Protection (AMP) filters that are configured for an affected device. This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for both virtual and hardware versions of Cisco Email Security Appliances, if the AMP feature is configured to scan incoming email attachments. More Information: CSCuz85823. Known Affected Releases: 10.0.0-082 9.7.0-125 9.7.1-066. Known Fixed Releases: 10.0.0-203 9.7.2-131.

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 confidence

A vulnerability in Cisco AsyncOS Email Security Appliances allows unauthenticated remote attackers to bypass Advanced Malware Protection (AMP) filters when scanning incoming email attachments. The vulnerability exists due to insufficient filtering logic in the email processing path, enabling malicious attachments to pass through without being scanned.

MitigationUpdate Cisco AsyncOS Software to fixed versions 10.0.0-203 or 9.7.2-131 or later. Verify AMP configuration is active after the update.

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
Email Security Appliance FirmwareOperating system
Affected:= 9.7.0-125= 9.7.1-06= 10.0.0-082

CVSS 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
Low
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Determine the installed AsyncOS version
    Log into the Cisco Email Security Appliance CLI and run the 'version' command, or access the web interface and navigate to System Administration > Software Update to view the current firmware version
    Affected if The displayed version matches exactly 9.7.0-125, 9.7.1-06, or 10.0.0-082
  2. Confirm the specific build number
    In the CLI, use 'version -verbose' or in the web interface check the full version string under About Appliance or System Health to confirm the exact build
    Affected if The full build version is one of the three affected versions listed (9.7.0-125, 9.7.1-06, or 10.0.0-082)
  3. Verify if Advanced Malware Protection is enabled
    In the ESA web interface, navigate to Mail Policies > Incoming Mail Policies, or in the CLI use 'amp' to check if AMP scanning is configured for incoming mail
    Affected if AMP is enabled and configured to scan attachments on incoming email; if AMP is disabled, the bypass does not apply in practice
  4. Check the AMP configuration for attachment scanning
    Navigate to Security Services > Advanced Malware Protection in the web interface, or use 'amp config' in the CLI to confirm that attachment scanning is active
    Affected if AMP is actively scanning attachments and the firmware version is one of the three affected versions

You are affected if your ESA runs AsyncOS version 9.7.0-125, 9.7.1-06, or 10.0.0-082 AND Advanced Malware Protection is enabled to scan incoming email attachments.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update Cisco AsyncOS Software to fixed versions 10.0.0-203 or 9.7.2-131 or later. Verify AMP configuration is active after the update.

Fix this in Email Security Appliance Firmware Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-6463 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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