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Web Security ApplianceApplication · Cisco

CVE-2018-0410

HIGH · 8.6 CVSS v3.0 Published 2018-08-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
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 web proxy functionality of Cisco AsyncOS Software for Cisco Web Security Appliances could allow an unauthenticated, remote attacker to exhaust system memory and cause a denial of service (DoS) condition on an affected system. The vulnerability exists because the affected software improperly manages memory resources for TCP connections to a targeted device. An attacker could exploit this vulnerability by establishing a high number of TCP connections to the data interface of an affected device via IPv4 or IPv6. A successful exploit could allow the attacker to exhaust system memory, which could cause the system to stop processing new connections and result in a DoS condition. System recovery may require manual intervention. Cisco Bug IDs: CSCvf36610.

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 memory management vulnerability exists in the web proxy functionality of Cisco AsyncOS Software for Web Security Appliances. The software improperly manages memory resources when handling TCP connections. An unauthenticated remote attacker can exploit this by establishing a high volume of TCP connections to the data interface (via IPv4 or IPv6), causing memory exhaustion and a denial of service condition that halts new connection processing.

MitigationApply the Cisco patch for CSCvf36610 when available. Consider implementing connection rate limiting on the data interface and network segmentation to reduce exposure to unauthenticated attackers until the patch can be applied.

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:= 9.1.1-074= 9.1.2-010= 9.1.2-022= 9.1.2-039= 10.1.0-204= 10.1.1-235= 10.5.1-270= 10.5.1-296= 10.5.2-042= 11.0.0-641

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
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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 Web Security Appliance model and firmware version
    Access the appliance CLI and run the command 'version' or 'show version' to display the installed AsyncOS version and build number
    Affected if The displayed version matches one of the affected builds: 9.1.1-074, 9.1.2-010, 9.1.2-022, 9.1.2-039, 10.1.0-204, 10.1.1-235, 10.5.1-270, 10.5.1-296, 10.5.2-042, or 11.0.0-641
  2. Verify web proxy functionality is enabled
    Log into the web interface or CLI and navigate to the proxy settings. In CLI, use 'proxyconfig' or 'show proxy' to check if the web proxy service is active
    Affected if The web proxy service is enabled and listening on the data interface
  3. Confirm data interface network exposure
    Use the CLI command 'interfaceconfig' or check the web interface network settings to identify which interfaces the proxy is bound to and whether they accept external connections
    Affected if The data interface with proxy enabled is directly accessible from untrusted networks (not behind a firewall or in a segmented VLAN)
  4. Check for connection pool exhaustion indicators
    Use the CLI command 'proxystats' or access the web interface dashboard to monitor active TCP connections and memory utilization statistics
    Affected if Connection counts are approaching platform limits or memory usage is abnormally high and not recovering

The environment is affected if the Cisco Web Security Appliance is running an affected AsyncOS build (listed above) with the web proxy enabled and the data interface exposed to untrusted network access.

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 Cisco patch for CSCvf36610 when available. Consider implementing connection rate limiting on the data interface and network segmentation to reduce exposure to unauthenticated attackers until the patch can be applied.

Fix this in Web Security Appliance Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2018-0410 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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