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AsyncosOperating system · Cisco

CVE-2017-12303

MEDIUM · 5.3 CVSS v3.0 Published 2017-11-16
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 Advanced Malware Protection (AMP) file filtering feature of Cisco AsyncOS Software for Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to bypass a configured AMP file filtering rule. The file types affected are zipped or archived file types. The vulnerability is due to incorrect and different file hash values when AMP scans the file. An attacker could exploit this vulnerability by sending a crafted email file attachment through the targeted device. An exploit could allow the attacker to bypass a configured AMP file filter. Cisco Bug IDs: CSCvf52943.

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 Web Security Appliance's Advanced Malware Protection (AMP) file filtering allows bypass of configured rules for zipped or archived email attachments. The vulnerability stems from incorrect file hash calculation during AMP scanning—the hash values differ between the scanned version and the actual file, enabling crafted malicious files to evade detection.

MitigationApply the vendor patch for Cisco Bug ID CSCvf52943. Until patched, implement supplementary email security controls such as additional content filters or attachment type restrictions to reduce the attack surface.

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:= 10.1.1-234= 10.1.1-235

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:3.0/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. Identify Cisco WSA deployment
    Confirm Cisco Web Security Appliance is in use by checking network infrastructure or querying the device hostname/IP via SNMP, Nmap, or documented network diagrams
    Affected if Device is not a Cisco WSA - this CVE does not apply
  2. Check AsyncOS version
    Log into the WSA CLI and run the `version` command, or access the web interface under System Administration > Software Update to view the current AsyncOS version
    Affected if AsyncOS version is NOT exactly 10.1.1-234 or 10.1.1-235 - these are the only affected versions
  3. Verify AMP is enabled
    Log into the WSA web interface, navigate to Security Services > Advanced Malware Protection, or use CLI command `ampconfig` to confirm AMP is turned on
    Affected if AMP is disabled - the vulnerability exists only when AMP is actively scanning files
  4. Confirm email attachment filtering rules exist
    In the WSA web interface, check the Mail Policies > Attachment Filtering rules, or use CLI command `attachmentfilter` to list configured rules that act on email attachments
    Affected if No attachment filtering rules are configured - the bypass only affects rules that filter zipped or archived email attachments

A user is affected if running Cisco WSA with AsyncOS exactly version 10.1.1-234 or 10.1.1-235, with AMP enabled and with email attachment filtering rules configured for zipped or archived files.

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 vendor patch for Cisco Bug ID CSCvf52943. Until patched, implement supplementary email security controls such as additional content filters or attachment type restrictions to reduce the attack surface.

Fix this in Asyncos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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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-2017-12303 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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