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Cisco Bug: CSCur07907 - Cisco Web Security Appliance (WSA) DNS Resolution Vulnerability

Last Modified

Feb 13, 2018

Products (1)

  • Cisco Web Security Appliance

Known Affected Releases


Description (partial)

A vulnerability in Domain Name Service (DNS) resolution function of the Cisco Web Security 
Appliance (WSA) could allow an unauthenticated, remote attacker to cause a partial denial 
of service (DoS) condition due to DNS name resolution failing through the device.

The vulnerability is due to the handling of DNS requests awaiting a DNS response when new, 
incoming DNS requests are received. An attacker could exploit this vulnerability by sending 
TCP proxy traffic to the WSA at a high rate. An exploit could allow the attacker to cause a 
partial DoS condition because DNS name resolution fails which results in the client receiving 
a HTTP 503 ''Service Unavailable'' error.

Device running with default configuration running an affected version of software.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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  • Known Fixed Releases
  • Related Community Discussions
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