dbcve.org
Web Security ApplianceApplication · Cisco

CVE-2017-3827

MEDIUM · 5.8 CVSS v3.0 Published 2017-02-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
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 Multipurpose Internet Mail Extensions (MIME) scanner of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA) and Web Security Appliances (WSA) could allow an unauthenticated, remote attacker to bypass configured user filters on the device. Affected Products: This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco ESA and Cisco WSA, both virtual and hardware appliances, that are configured with message or content filters to scan incoming email attachments on the ESA or services scanning content of web access on the WSA. More Information: SCvb91473, CSCvc76500. Known Affected Releases: 10.0.0-203 9.9.9-894 WSA10.0.0-233.

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 MIME scanner of Cisco AsyncOS Software for Email Security Appliances (ESA) and Web Security Appliances (WSA) allows unauthenticated remote attackers to bypass configured message or content filters that scan email attachments or web content, potentially letting malicious attachments or content pass through unsanctioned.

MitigationApply the first fixed release of Cisco AsyncOS Software for ESA and WSA devices. Prior to patching, review filter configurations and consider additional perimeter controls to inspect MIME-encoded content.

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
Web Security ApplianceApplication
Affected:= 10.0.0-082= 10.0.0-124= 10.0.0-125= 10.0.0-203= 10.0.0-232
Email Security Appliance FirmwareOperating system
Affected:= 9.9.6-026= 9.9.9-894= 10.0.0-082= 10.0.0-124= 10.0.0-125= 10.0.0-203= 10.0.0-232

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
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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 device is Cisco ESA or WSA
    Access the appliance CLI or web interface and identify the device type. In CLI, use 'show version' or 'systemstatus' to confirm the device model.
    Affected if Device is not a Cisco Email Security Appliance or Web Security Appliance (this CVE only affects those products)
  2. Check installed firmware version
    In the appliance CLI, run 'version' or 'show version' to display the running AsyncOS firmware version. Compare against the affected version list: WSA 10.0.0-082, 10.0.0-124, 10.0.0-125, 10.0.0-203, 10.0.0-232; ESA 9.9.6-026, 9.9.9-894, 10.0.0-082, 10.0.0-124, 10.0.0-125, 10.0.0-203, 10.0.0-232
    Affected if The installed version exactly matches one of the listed affected versions
  3. Verify content or message filters for attachment scanning are configured
    In the web interface, go to Security Services > Content Filters (ESA) or Security Services > Web Filters (WSA) to list active filters. Alternatively in CLI, use 'filters' or 'contentfilters' command to display configured filters.
    Affected if At least one content filter or message filter that scans email attachments or web content is enabled (the vulnerability bypasses these specific filters)
  4. Confirm MIME scanning is enabled
    In the ESA web interface, verify under Mail Policies > Incoming Mail Policies that attachment scanning or MIME type filtering is active. In WSA, check under Web Security Services > MIME Types. In CLI, use 'mimescan' or 'attachment' inspection commands.
    Affected if MIME scanner or attachment content inspection is turned on (the bypass only affects these scanning features)

You are affected if you run Cisco ESA or WSA with a firmware version matching one of the listed versions AND have content/message filters or MIME scanning enabled for attachment or web content inspection.

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

Apply the first fixed release of Cisco AsyncOS Software for ESA and WSA devices. Prior to patching, review filter configurations and consider additional perimeter controls to inspect MIME-encoded content.

Fix this in Web Security Appliance Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2017-3827 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2017-3827 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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