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Email Security Appliance FirmwareOperating system · Cisco

CVE-2016-6462

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: CSCva13456. Known Affected Releases: 10.0.0-082 10.0.0-125 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 the email filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances allows an unauthenticated, remote attacker to bypass Advanced Malware Protection (AMP) filters that are configured to scan incoming email attachments. This occurs in all releases prior to 10.0.0-203 or 9.7.2-131.

MitigationUpgrade Cisco AsyncOS Software to the fixed release (10.0.0-203 or 9.7.2-131) or later. Ensure AMP is properly configured for incoming email attachment scanning.

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:= 9.7.1-06= 10.0.0-082= 10.0.0-125

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. Identify the device model
    Log into the Cisco Email Security Appliance web interface or CLI and check the device model/hostname. Confirm it is a Cisco Email Security Appliance (ESA) running Cisco AsyncOS Software.
    Affected if Device is not a Cisco ESA running AsyncOS - this CVE does not apply
  2. Check the installed AsyncOS version
    In the ESA CLI, run the command 'version' or 'show version'. In the web interface, navigate to System Administration > Software Update to view the current AsyncOS version.
    Affected if Version is 9.7.1-06, 10.0.0-082, or 10.0.0-125, or any version prior to 9.7.2-131 or 10.0.0-203
  3. Verify AMP is configured for incoming email scanning
    In the ESA web interface, go to Security Services > AMP. Check if AMP is enabled and verify that incoming email attachment scanning is turned on under the AMP configuration settings.
    Affected if AMP is enabled but incoming email attachment scanning is configured - the bypass vulnerability can be triggered
  4. Confirm scanning filters are active
    In the ESA web interface, navigate to Mail Policies > Incoming Mail Policies. Verify that AMP scanning is applied to at least one incoming mail policy that handles attachments.
    Affected if AMP scanning policies are active for incoming email - the vulnerability can be exploited

A user is affected if they run a Cisco ESA with AsyncOS versions prior to 9.7.2-131 or 10.0.0-203 AND have AMP enabled for incoming email attachment scanning.

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

Upgrade Cisco AsyncOS Software to the fixed release (10.0.0-203 or 9.7.2-131) or later. Ensure AMP is properly configured for incoming email attachment scanning.

Fix this in Email Security Appliance Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,980
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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-2016-6462 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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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