dbcve.org
AsyncosOperating system · Cisco

CVE-2020-26082

MEDIUM · 5.3 CVSS v3.1 Published 2023-08-04
Fix available
A fix is available. Upgrade to 13.5.2 or later.
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 zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass content filters that are configured on an affected device. The vulnerability is due to improper handling of password-protected zip files. An attacker could exploit this vulnerability by sending a malicious file inside a crafted zip-compressed file to an affected device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.

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 Email Security Appliance allows unauthenticated remote attackers to bypass content filters by embedding malicious content in password-protected zip files. The ESA's content filter cannot properly inspect password-protected archives, allowing malicious files to pass through unchecked.

MitigationApply the vendor-provided Cisco security patch for CVE-2020-26082. In the interim, consider implementing additional email security controls or secondary filtering layers to inspect password-protected attachments.

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
AsyncosOperating system
Affected:< 13.5.2

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
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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. Confirm Cisco ESA product in use
    Log into the ESA web interface or CLI and identify the appliance type. Verify the device is an Email Security Appliance (ESA) running AsyncOS software.
    Affected if The device is not a Cisco Email Security Appliance running AsyncOS.
  2. Determine AsyncOS version
    In the ESA CLI, run the 'version' command, or in the web GUI navigate to System Administration > Software Update to view the installed AsyncOS version.
    Affected if Unable to retrieve the AsyncOS version from the appliance.
  3. Compare version to affected threshold
    Compare the installed AsyncOS version against the affected range: versions prior to 13.5.2 are vulnerable (for example, 13.0.0, 13.5.0, 13.5.1-116, 14.0.0, etc.). Versions 13.5.2 and later are not affected.
    Affected if The installed AsyncOS version is lower than 13.5.2.
  4. Check content filter configuration
    In the ESA web GUI, navigate to Mail Policies > Incoming Mail Policies or Outgoing Mail Policies to verify if content filters are enabled and configured to inspect attachments.
    Affected if Content filters are active and configured to inspect zip archives - the vulnerability allows malicious content in password-protected zip files to bypass these filters.

You are affected if your Cisco ESA runs AsyncOS version lower than 13.5.2 and you rely on content filters to inspect 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.

dbcve · scoped
Upgrade available Upgrade to 13.5.2 or later
Fixed in 13.5.2
Interim mitigation

Apply the vendor-provided Cisco security patch for CVE-2020-26082. In the interim, consider implementing additional email security controls or secondary filtering layers to inspect password-protected attachments.

Recommended fix High confidence

AsyncOS 13.5.2 or later

  1. Confirm current AsyncOS version by accessing the ESA CLI and running the 'version' command
  2. Schedule a maintenance window for the upgrade to minimize disruption
  3. Download AsyncOS 13.5.2 or later from Cisco's official support portal (sec.cloudapps.cisco.com)
  4. Access the ESA CLI or web interface and navigate to the System Upgrade options
  5. Upload the AsyncOS upgrade image to the ESA
  6. Initiate the upgrade process and allow the system to reboot
  7. After reboot, verify the new version by running the 'version' command in the CLI
  8. Verify that content filters are functioning correctly with password-protected zip files

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Asyncos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,300
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,680.

Scan for this in your stack

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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-2020-26082 in production — separate from our analysis above.

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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