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Email Security ApplianceApplication · Cisco

CVE-2020-3134

MEDIUM · 6.5 CVSS v3.1 Published 2020-01-26
Fix available
A fix is available. Upgrade to 13.0 or later.
See remediation →
74/100
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 zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of zip files. An attacker could exploit this vulnerability by sending an email message with a crafted zip-compressed attachment. A successful exploit could trigger a restart of the content-scanning process, causing a temporary DoS condition. This vulnerability affects Cisco AsyncOS Software for Cisco ESA releases earlier than 13.0.

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 zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance allows unauthenticated remote attackers to send crafted zip-compressed attachments via email that trigger improper validation, causing a restart of the content-scanning process and resulting in temporary denial of service.

MitigationUpgrade to Cisco AsyncOS Software version 13.0 or later, as releases earlier than 13.0 are affected.

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 ApplianceApplication
Affected:< 13.0

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
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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 checks

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

  1. Confirm Cisco Email Security Appliance is in use
    Log into the ESA web interface or CLI and identify the device model. This vulnerability affects only the Cisco Email Security Appliance product line.
    Affected if The device is not a Cisco Email Security Appliance (for example, it is a different Cisco security product)
  2. Determine installed AsyncOS version
    In the ESA web interface, go to System Administration > Software Update, or run the 'version' command in the CLI to display the currently installed AsyncOS software version.
    Affected if Unable to retrieve a version number from the device
  3. Compare version to affected range
    Compare the installed AsyncOS version number to the affected range. Versions earlier than 13.0 are affected. The version format typically appears as major.release (for example, 12.5, 12.5.1, 12.5.2).
    Affected if The installed version is less than 13.0 (for example, 12.5.x, 12.0.x, 11.x)
  4. Verify content scanning is active
    In the ESA web interface, go to Mail Policies > Incoming Mail Policies or Outgoing Mail Policies. Confirm that content scanning features are enabled for at least one mail policy. This vulnerability triggers when the content-scanning process handles the crafted attachment.
    Affected if Content scanning is disabled on all mail policies (though this is unlikely as it is the primary function of the ESA)

The environment is affected if the Cisco Email Security Appliance runs AsyncOS version earlier than 13.0 and content scanning is active, as the vulnerability resides in the zip decompression engine used during email attachment processing.

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
Upgrade available Upgrade to 13.0 or later
Fixed in 13.0
Interim mitigation

Upgrade to Cisco AsyncOS Software version 13.0 or later, as releases earlier than 13.0 are affected.

Fix this in Email Security Appliance Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

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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-2020-3134 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data